1 00:00:00,866 --> 00:00:03,800 ♪ 2 00:00:05,966 --> 00:00:08,566 NARRATOR: Notre Dame de Paris... 3 00:00:08,600 --> 00:00:10,933 A treasured icon of Gothic architecture 4 00:00:10,966 --> 00:00:13,700 {\an1}and medieval engineering, 5 00:00:13,733 --> 00:00:15,633 {\an1}built from glass, 6 00:00:15,666 --> 00:00:17,200 stone, 7 00:00:17,233 --> 00:00:18,833 and timber over the course 8 00:00:18,866 --> 00:00:20,133 {\an1}of two centuries. 9 00:00:20,166 --> 00:00:26,233 For 850 years, this 226-foot-tall cathedral 10 00:00:26,266 --> 00:00:29,633 {\an1}has been an enduring symbol at the heart 11 00:00:29,666 --> 00:00:32,300 {\an1}of French culture, and more... 12 00:00:32,333 --> 00:00:34,966 JOHN DICKAS: Notre Dame is one of humanity's greatest 13 00:00:35,000 --> 00:00:36,800 {\an1}artistic and architectural achievements. 14 00:00:36,833 --> 00:00:39,042 {\an1}PATRICK CHAUVET (translated): Notre Dame is not just Paris. 15 00:00:39,066 --> 00:00:40,166 It's France. 16 00:00:40,200 --> 00:00:41,200 {\an1}And beyond France, 17 00:00:41,233 --> 00:00:42,400 it's the world. 18 00:00:42,433 --> 00:00:46,233 NARRATOR: But on April 15, 2019, 19 00:00:46,266 --> 00:00:49,500 {\an1}a disaster that threatens to destroy it all strikes. 20 00:00:51,400 --> 00:00:56,466 A massive fire raging out of control... 21 00:00:56,500 --> 00:00:57,400 {\an1}(person gasping, cries out) 22 00:00:57,433 --> 00:00:58,866 MAN: Oh, my God! 23 00:00:58,900 --> 00:01:02,433 {\an8}NARRATOR: leaves the cathedral in ruins. 24 00:01:02,466 --> 00:01:04,033 ♪ 25 00:01:04,066 --> 00:01:06,733 Now, an elite team of engineers, 26 00:01:06,766 --> 00:01:07,833 scientists, 27 00:01:07,866 --> 00:01:10,400 {\an1}and master craftspeople, 28 00:01:10,433 --> 00:01:13,100 battle to save this fragile structure 29 00:01:13,133 --> 00:01:15,033 {\an1}from a catastrophic collapse. 30 00:01:15,066 --> 00:01:16,800 {\an8}(alarm blaring) LISE LEROUX (in French): 31 00:01:19,666 --> 00:01:21,033 ♪ 32 00:01:21,066 --> 00:01:23,933 NARRATOR: Out of tragedy, an opportunity is born... 33 00:01:23,966 --> 00:01:25,900 {\an8}Oh! 34 00:01:25,933 --> 00:01:27,700 {\an7}This is a dating fossil. 35 00:01:27,733 --> 00:01:31,500 {\an8}NARRATOR: to solve archaeological mysteries 36 00:01:31,533 --> 00:01:32,676 {\an1}and understand the very fabric 37 00:01:32,700 --> 00:01:35,566 {\an1}of this medieval megastructure 38 00:01:35,600 --> 00:01:36,900 {\an1}like never before. 39 00:01:36,933 --> 00:01:39,666 CLAUDINE LOISEL: We can identify each chemical element. 40 00:01:39,700 --> 00:01:40,900 ♪ 41 00:01:40,933 --> 00:01:42,466 NARRATOR: Can clues from the past 42 00:01:42,500 --> 00:01:47,833 {\an1}help save and rebuild this landmark? 43 00:01:47,866 --> 00:01:49,300 {\an1}And can pioneering technology 44 00:01:49,333 --> 00:01:51,100 {\an1}prevent another disaster? 45 00:01:51,133 --> 00:01:53,766 {\an1}(mechanism whirring) 46 00:01:53,800 --> 00:01:55,233 {\an1}What we are producing today 47 00:01:55,266 --> 00:02:00,300 {\an1}will be the information usable for the next generations. 48 00:02:00,333 --> 00:02:01,866 NARRATOR: "Saving Notre Dame"... 49 00:02:01,900 --> 00:02:04,800 {\an1}right now, on "NOVA." 50 00:02:04,833 --> 00:02:12,833 ♪ 51 00:02:19,766 --> 00:02:24,866 ♪ 52 00:02:24,900 --> 00:02:26,509 ANNOUNCER: Major funding for "NOVA" is provided by the following: 53 00:02:26,533 --> 00:02:29,766 ♪ 54 00:02:29,800 --> 00:02:33,400 NARRATOR: The Cathedral of Notre Dame de Paris... 55 00:02:33,433 --> 00:02:37,033 {\an1}an 850-year-old Gothic wonder. 56 00:02:37,066 --> 00:02:38,366 {\an1}It's the heart of France. 57 00:02:38,400 --> 00:02:41,833 {\an1}The distance from Paris to all other places 58 00:02:41,866 --> 00:02:45,366 {\an1}is traditionally measured from this iconic structure. 59 00:02:45,400 --> 00:02:46,833 SANDRON: There is a continuation, 60 00:02:46,866 --> 00:02:49,500 {\an7}a historical continuation, 61 00:02:49,533 --> 00:02:51,666 {\an7}from the Middle Ages to nowadays. 62 00:02:51,700 --> 00:02:57,366 {\an1}And it's very important to build a kind of identity. 63 00:02:57,400 --> 00:03:00,300 {\an1}Notre Dame is one of the monuments 64 00:03:00,333 --> 00:03:04,800 {\an1}which achieved this identity. 65 00:03:04,833 --> 00:03:06,342 {\an7}For Christians, it's a place of worship, right? 66 00:03:06,366 --> 00:03:07,942 {\an7}And, and for those of us with different beliefs, 67 00:03:07,966 --> 00:03:11,300 {\an7}it's one of just this incredibleartistic and historic landmark. 68 00:03:11,333 --> 00:03:13,166 {\an1}You've had coronations there, 69 00:03:13,200 --> 00:03:15,966 {\an1}you've had the crowning of Napoleon and King Henry. 70 00:03:16,000 --> 00:03:17,266 {\an1}There's just so much attached 71 00:03:17,300 --> 00:03:18,566 {\an7}to the cathedral. 72 00:03:18,600 --> 00:03:21,033 {\an8}NARRATOR: But Notre Dame is much more than that. 73 00:03:21,066 --> 00:03:24,266 {\an7}It's also a pinnacle of medieval engineering. 74 00:03:26,266 --> 00:03:29,700 {\an7}The cathedral can hold 9,000 worshippers, 75 00:03:29,733 --> 00:03:32,266 {\an7}and its 100-foot tall walls 76 00:03:32,300 --> 00:03:38,066 {\an7}contain more than 32,000 square feet of stained glass. 77 00:03:38,100 --> 00:03:40,833 {\an7}The ceiling is a series of domed Gothic vaults 78 00:03:40,866 --> 00:03:45,866 {\an7}that hold up the cathedral from the inside. 79 00:03:45,900 --> 00:03:49,033 {\an7}A complex 550-ton web of timber 80 00:03:49,066 --> 00:03:51,366 {\an1}forms a cross-shaped roof, 81 00:03:51,400 --> 00:03:54,533 {\an1}topped with 1,300 lead tiles 82 00:03:54,566 --> 00:03:57,700 {\an1}and a 300-foot tall central spire. 83 00:04:01,100 --> 00:04:05,366 {\an1}Wrapped around the church are 28 flying buttresses, 84 00:04:05,400 --> 00:04:09,866 {\an1}limestone arches that brace the walls from the outside. 85 00:04:09,900 --> 00:04:13,033 {\an1}And at the front, two mighty towers, 86 00:04:13,066 --> 00:04:16,966 {\an1}with ten massive bronze bells inside, 87 00:04:17,000 --> 00:04:22,366 {\an1}soar over 226 feet into the sky over Paris. 88 00:04:23,533 --> 00:04:26,466 SANDRON: The construction took many generations. 89 00:04:26,500 --> 00:04:29,400 {\an1}Architecture was not learned at the university, 90 00:04:29,433 --> 00:04:35,133 {\an1}so the architects and allworkers learned mostly on site. 91 00:04:35,166 --> 00:04:38,900 NARRATOR: Along the way, there were many setbacks. 92 00:04:38,933 --> 00:04:42,666 {\an1}In 1789, at the height of the French Revolution, 93 00:04:42,700 --> 00:04:43,933 {\an1}anti-Catholic forces 94 00:04:43,966 --> 00:04:47,500 {\an1}destroy parts of the Cathedral. 95 00:04:47,533 --> 00:04:50,000 {\an1}A newly secular France leaves Notre Dame 96 00:04:50,033 --> 00:04:52,366 {\an1}in a state of neglect. 97 00:04:52,400 --> 00:04:56,566 {\an1}But when Victor Hugo writes "The Hunchback of Notre Dame" 98 00:04:56,600 --> 00:05:01,266 {\an1}in 1831, it sparks a $60 million restoration, 99 00:05:01,300 --> 00:05:05,266 {\an1}that tops out the cathedral with a new roof 100 00:05:05,300 --> 00:05:09,200 and a 750-ton timber and lead spire. 101 00:05:13,133 --> 00:05:17,966 {\an1}Periodic renovations continue to this day. 102 00:05:18,000 --> 00:05:20,333 {\an1}On April 15, 2019, 103 00:05:20,366 --> 00:05:25,100 {\an1}Notre Dame is wrapped in 550 tons of scaffolding, 104 00:05:25,133 --> 00:05:26,466 as workers begin 105 00:05:26,500 --> 00:05:31,133 {\an1}a $6 million operation toshore up the cathedral's spire. 106 00:05:31,166 --> 00:05:33,633 {\an7}CHAUVET AND MADO: 107 00:05:33,666 --> 00:05:35,666 {\an8}CHAUVET: 108 00:05:35,700 --> 00:05:37,233 NARRATOR: Notre Dame's rector, 109 00:05:37,266 --> 00:05:39,033 {\an1}Father Patrick Chauvet, 110 00:05:39,066 --> 00:05:40,433 {\an1}has finished evening worship. 111 00:05:40,466 --> 00:05:45,833 {\an1}His world is about to be turned upside down. 112 00:05:45,866 --> 00:05:47,442 {\an1}CHAUVET (translated): I stopped here because 113 00:05:47,466 --> 00:05:49,866 {\an1}I really like Mado. 114 00:05:49,900 --> 00:05:53,700 {\an7}She offered me a drink, and when she came back she said, 115 00:05:53,733 --> 00:05:58,200 {\an7}"Father, there's smoke above the spire of the cathedral." 116 00:05:58,233 --> 00:06:03,566 {\an7}So I left my drink and went back to check there was nobody 117 00:06:03,600 --> 00:06:06,700 {\an1}in the cathedral. 118 00:06:06,733 --> 00:06:11,133 NARRATOR: At 6:18 p.m., a sensor detects smoke 119 00:06:11,166 --> 00:06:13,566 {\an1}in the medieval roof timbers. 120 00:06:13,600 --> 00:06:17,533 {\an1}The system sends a coded fire alert to the security team. 121 00:06:17,566 --> 00:06:19,800 {\an1}Instead of heading straight for the roof, 122 00:06:19,833 --> 00:06:23,166 {\an1}a guard is dispatched to the sacristy building nearby, 123 00:06:23,200 --> 00:06:25,100 {\an1}to check for a fire. 124 00:06:25,133 --> 00:06:27,033 {\an1}But he finds nothing. 125 00:06:27,066 --> 00:06:29,633 {\an1}He climbs up into the church attic. 126 00:06:29,666 --> 00:06:34,000 {\an1}But by the time he gets there, he's too late. 127 00:06:34,033 --> 00:06:37,066 {\an1}The fire has been burning for almost 30 minutes 128 00:06:37,100 --> 00:06:40,400 {\an1}and has spread across the roof. 129 00:06:40,433 --> 00:06:44,400 (siren blaring) 130 00:06:44,433 --> 00:06:45,942 DICKAS: And there was this horrifyingly 131 00:06:45,966 --> 00:06:49,633 huge plume of smoke billowing up out of it. 132 00:06:49,666 --> 00:06:50,733 It was surreal. 133 00:06:50,766 --> 00:06:51,809 {\an1}I'd never seen anything like that before. 134 00:06:51,833 --> 00:06:54,100 (sirens blaring) 135 00:06:54,133 --> 00:06:55,433 You saw the fire trucks come up 136 00:06:55,466 --> 00:06:57,333 {\an1}alongside the cathedral and ladders went up, 137 00:06:57,366 --> 00:07:00,233 {\an1}and the hoses came out, you could see that the ladders 138 00:07:00,266 --> 00:07:02,400 {\an1}were just too small for a building of this size 139 00:07:02,433 --> 00:07:04,666 {\an1}and the hoses were not nearly big enough 140 00:07:04,700 --> 00:07:05,733 {\an1}for this kind of blaze. 141 00:07:05,766 --> 00:07:06,842 {\an1}It was tragic; the resources 142 00:07:06,866 --> 00:07:08,633 {\an1}that were available were not going to be 143 00:07:08,666 --> 00:07:10,576 {\an1}what was needed to bring this thing under control. 144 00:07:10,600 --> 00:07:12,066 ♪ 145 00:07:12,100 --> 00:07:13,366 {\an1}A lot of us realized 146 00:07:13,400 --> 00:07:16,133 {\an1}that this fire was just going to ravage the cathedral. 147 00:07:16,166 --> 00:07:17,609 {\an1}MIKA (translated): We saw what was happening, 148 00:07:17,633 --> 00:07:19,000 {\an1}but we were powerless, 149 00:07:19,033 --> 00:07:20,866 {\an1}we could do nothing. 150 00:07:20,900 --> 00:07:22,600 {\an1}It really looked like the end of the world. 151 00:07:22,633 --> 00:07:25,233 {\an1}It was so chaotic. 152 00:07:25,266 --> 00:07:28,066 {\an7}A delay in responding to a fire of this nature 153 00:07:28,100 --> 00:07:29,366 {\an7}is absolutely critical. 154 00:07:29,400 --> 00:07:32,833 {\an1}A small fire burning locally is a very different thing 155 00:07:32,866 --> 00:07:35,866 {\an1}than ten minutes laterwhen all of the timber elements 156 00:07:35,900 --> 00:07:37,233 {\an1}are involved. 157 00:07:37,266 --> 00:07:38,600 {\an1}So in a situation like this, 158 00:07:38,633 --> 00:07:40,600 {\an1}five, ten, 30 minutes can make all the difference. 159 00:07:40,633 --> 00:07:46,800 NARRATOR: This delay will have huge repercussions. 160 00:07:46,833 --> 00:07:48,109 As firefighters arrive on scene, 161 00:07:48,133 --> 00:07:50,166 {\an1}so does one of France's chief architects 162 00:07:50,200 --> 00:07:52,133 {\an1}of historic monuments, 163 00:07:52,166 --> 00:07:53,766 Rémi Fromont. 164 00:07:53,800 --> 00:07:55,642 {\an1}FROMONT (translated): I managed to pass the police checkpoint 165 00:07:55,666 --> 00:07:57,800 {\an1}and I joined the firefighters. 166 00:07:57,833 --> 00:08:02,233 NARRATOR: As the inferno rages at the top of the cathedral, 167 00:08:02,266 --> 00:08:04,533 {\an1}Rémi risks his life to venture inside 168 00:08:04,566 --> 00:08:07,433 {\an1}with the firefighters. 169 00:08:07,466 --> 00:08:09,542 {\an8}(translated): We did a tour of the cathedral several times. 170 00:08:09,566 --> 00:08:11,666 {\an7}We checked the nave. 171 00:08:11,700 --> 00:08:15,166 I saw the flames and saw the blaze. 172 00:08:15,200 --> 00:08:17,966 {\an1}I gave them all the advice that I could. 173 00:08:18,000 --> 00:08:21,766 NARRATOR: Within minutes, the firefighters are pumping tons of water 174 00:08:21,800 --> 00:08:23,066 {\an1}into the roof space, 175 00:08:23,100 --> 00:08:26,066 but to no avail. 176 00:08:26,100 --> 00:08:27,466 To the horror of the growing crowd, 177 00:08:27,500 --> 00:08:29,200 the fire engulfs the iconic spire. 178 00:08:29,233 --> 00:08:32,733 ♪ 179 00:08:32,766 --> 00:08:34,600 {\an1}The world watches helplessly 180 00:08:34,633 --> 00:08:39,766 {\an1}as the 750 ton oak and lead masterpiece gives way. 181 00:08:39,800 --> 00:08:41,400 (people gasping) 182 00:08:41,433 --> 00:08:43,033 MAN: Oh, my God! 183 00:08:43,066 --> 00:08:44,600 Oh, my God... 184 00:08:44,633 --> 00:08:46,766 That is awful. 185 00:08:50,266 --> 00:08:51,500 BISBY: When the spire 186 00:08:51,533 --> 00:08:55,200 {\an1}fell into the roof, additional ventilation 187 00:08:55,233 --> 00:08:56,933 will have caused more oxygen-rich air 188 00:08:56,966 --> 00:08:59,666 {\an1}to be sucked in at the bottom of the compartment. 189 00:08:59,700 --> 00:09:01,166 {\an1}That influx of oxygen 190 00:09:01,200 --> 00:09:04,000 {\an1}could have caused an increase in the severity of the fire 191 00:09:04,033 --> 00:09:07,866 {\an1}within Notre Dame. 192 00:09:07,900 --> 00:09:10,466 (translated): All of a sudden, there was a huge, huge ball of fire 193 00:09:10,500 --> 00:09:12,766 {\an1}rising out of the cathedral. 194 00:09:12,800 --> 00:09:17,766 {\an1}It was spitting ash and debriseverywhere, so we took shelter. 195 00:09:17,800 --> 00:09:21,033 DICKAS: It was just devastating to watch. 196 00:09:21,066 --> 00:09:23,433 {\an1}We were suddenly really aware 197 00:09:23,466 --> 00:09:25,576 {\an1}that of, of how easily this whole thing could come down. 198 00:09:25,600 --> 00:09:27,733 {\an8}♪ 199 00:09:27,766 --> 00:09:29,433 {\an8}NARRATOR: 90 minutes after the fire begins, 200 00:09:29,466 --> 00:09:34,566 {\an8}the entire roof of the cathedral is ablaze. 201 00:09:34,600 --> 00:09:37,433 {\an1}Inside, it's become even more dangerous for Rémi 202 00:09:37,466 --> 00:09:40,133 {\an1}and the firefighters. 203 00:09:40,166 --> 00:09:43,800 {\an1}Getting this fire under control looks impossible. 204 00:09:43,833 --> 00:09:44,942 {\an1}FROMONT (translated): The fire on the ground, 205 00:09:44,966 --> 00:09:46,700 {\an1}smoke everywhere, a hole in the ceiling. 206 00:09:46,733 --> 00:09:48,833 {\an1}We were trying to understand what was going on, 207 00:09:48,866 --> 00:09:51,666 {\an1}where the problems where, check what had collapsed 208 00:09:51,700 --> 00:09:53,633 {\an1}and if there were other risks. 209 00:09:53,666 --> 00:09:56,800 {\an8}NARRATOR: A southeasterly wind picks up 210 00:09:56,833 --> 00:09:59,766 {\an7}and pushes the blaze towards the famous bell towers. 211 00:09:59,800 --> 00:10:01,142 {\an7}FROMONT (translated): If the bell towers catch fire, 212 00:10:01,166 --> 00:10:02,333 {\an7}and the bells fall, 213 00:10:02,366 --> 00:10:04,933 {\an1}then they will smash through everything below. 214 00:10:04,966 --> 00:10:08,133 NARRATOR: Inside the ingeniously engineered 215 00:10:08,166 --> 00:10:09,933 {\an7}13th century north tower 216 00:10:09,966 --> 00:10:14,500 {\an1}a scaffold of wooden beams holds eight bells. 217 00:10:14,533 --> 00:10:18,233 {\an1}The biggest weighing more than four tons. 218 00:10:18,266 --> 00:10:20,100 {\an1}If the beams burn through, 219 00:10:20,133 --> 00:10:23,633 {\an1}they'll spark a fatal chain reaction, 220 00:10:23,666 --> 00:10:26,433 {\an1}causing the bells to fall like wrecking balls, 221 00:10:26,466 --> 00:10:31,633 {\an1}destroying the tower's wooden backbone. 222 00:10:31,666 --> 00:10:36,933 {\an1}If the tower falls, it could trigger a deadly domino effect 223 00:10:36,966 --> 00:10:42,200 that brings down the entire cathedral. 224 00:10:42,233 --> 00:10:44,733 (sirens blaring) 225 00:10:44,766 --> 00:10:46,600 To avert this catastrophic collapse, 226 00:10:46,633 --> 00:10:49,600 the firefighters have no option 227 00:10:49,633 --> 00:10:52,000 {\an1}but to venture deeper inside. 228 00:10:52,033 --> 00:10:54,109 {\an1}CHAUVET (translated): President Macron said: "No doubt, 229 00:10:54,133 --> 00:10:56,000 we must send the firefighters in. 230 00:10:56,033 --> 00:10:57,333 {\an1}The cathedral must be saved." 231 00:10:57,366 --> 00:10:58,900 ♪ 232 00:10:58,933 --> 00:11:00,309 {\an1}FROMONT (translated): We headed to the North tower 233 00:11:00,333 --> 00:11:03,533 {\an1}just when the flames had reached the belfry. 234 00:11:03,566 --> 00:11:05,966 ♪ 235 00:11:06,000 --> 00:11:08,666 {\an1}The firefighters also knew it well. 236 00:11:08,700 --> 00:11:10,800 {\an1}We were guiding each other. 237 00:11:10,833 --> 00:11:17,466 ♪ 238 00:11:17,500 --> 00:11:20,866 NARRATOR: To douse the fire on the roof, firefighters pump water 239 00:11:20,900 --> 00:11:23,733 {\an1}from the River Seine and feed it to fire trucks 240 00:11:23,766 --> 00:11:25,700 {\an1}around the cathedral. 241 00:11:25,733 --> 00:11:28,966 {\an1}But to stop the towerscollapsing they must send a team 242 00:11:29,000 --> 00:11:31,433 {\an1}into the burning structure. 243 00:11:31,466 --> 00:11:35,033 {\an1}Their mission: drop hoses in between the towers 244 00:11:35,066 --> 00:11:38,966 {\an1}and fight the fire spreading from the roof. 245 00:11:39,000 --> 00:11:41,366 {\an1}But the steady wind doesn't let up. 246 00:11:41,400 --> 00:11:44,533 {\an1}And despite their efforts, the timber frame holding the bells 247 00:11:44,566 --> 00:11:47,433 {\an1}has caught fire and could trigger the destruction 248 00:11:47,466 --> 00:11:50,133 {\an1}of the cathedral at any moment. 249 00:11:50,166 --> 00:11:53,533 {\an7}So the team must drag their hoses to the top of the tower 250 00:11:53,566 --> 00:11:57,966 {\an1}and soak the timber frame to prevent the unthinkable. 251 00:12:03,500 --> 00:12:05,033 {\an7}Throughout the night, 252 00:12:05,066 --> 00:12:08,433 {\an7}the fate of Notre Dame hangs in the balance. 253 00:12:08,466 --> 00:12:12,033 {\an7}Eventually the firefighters get the upper hand. 254 00:12:12,066 --> 00:12:16,366 {\an7}The flames have been beaten back and only glowing embers 255 00:12:16,400 --> 00:12:18,700 {\an1}light up the night sky. 256 00:12:18,733 --> 00:12:21,933 Nobody knows how the fire started. 257 00:12:21,966 --> 00:12:24,400 {\an1}An investigation begins. 258 00:12:24,433 --> 00:12:27,033 But for now, the urgent question: 259 00:12:27,066 --> 00:12:29,500 {\an1}how damaged is the structure 260 00:12:29,533 --> 00:12:32,700 {\an1}and can it ever be rebuilt? 261 00:12:32,733 --> 00:12:35,266 {\an1}President Macron pledges to restore the cathedral 262 00:12:35,300 --> 00:12:37,066 in five years. 263 00:12:37,100 --> 00:12:39,900 (translated): Tonight, I tell you very solemnly, 264 00:12:39,933 --> 00:12:44,800 {\an1}we will rebuild this cathedral together. 265 00:12:44,833 --> 00:12:50,766 NARRATOR: Meanwhile, the world keeps vigil for Notre Dame. 266 00:12:50,800 --> 00:12:54,700 {\an1}(crowd singing in French) 267 00:12:56,833 --> 00:12:58,733 NARRATOR: Daylight reveals the full extent 268 00:12:58,766 --> 00:13:02,600 {\an1}of the terrible destruction wrought by the fire. 269 00:13:02,633 --> 00:13:04,000 {\an8}♪ 270 00:13:04,033 --> 00:13:07,766 {\an7}The oak roof and spire are completely destroyed. 271 00:13:07,800 --> 00:13:11,066 {\an7}Tons of toxic lead that covered the roof 272 00:13:11,100 --> 00:13:12,700 {\an7}have been sprayed into the air, 273 00:13:12,733 --> 00:13:14,533 {\an7}contaminating the site. 274 00:13:14,566 --> 00:13:17,866 {\an1}Burned roof timbers cover the vaulting. 275 00:13:17,900 --> 00:13:21,033 {\an1}Three gaping holes in the stone vaults 276 00:13:21,066 --> 00:13:23,066 {\an1}weaken the entire structure. 277 00:13:23,100 --> 00:13:27,333 {\an1}And the 550 ton scorched carcass of scaffolding 278 00:13:27,366 --> 00:13:29,800 {\an1}could collapse at any moment, 279 00:13:29,833 --> 00:13:33,933 {\an1}something unthinkableto those tasked with preserving 280 00:13:33,966 --> 00:13:36,700 {\an1}France's rich cultural heritage. 281 00:13:36,733 --> 00:13:38,742 {\an1}PHILLIPE VILLENEUVE (translated): I'm in front of my cathedral, 282 00:13:38,766 --> 00:13:39,933 {\an1}which is in this state. 283 00:13:39,966 --> 00:13:41,666 I need to work. 284 00:13:41,700 --> 00:13:43,500 NARRATOR: Phillipe Villeneuve is in charge 285 00:13:43,533 --> 00:13:46,366 of historic monuments in France. 286 00:13:46,400 --> 00:13:49,566 {\an1}This is the cathedral that inspired him 287 00:13:49,600 --> 00:13:51,600 {\an1}to become an architect. 288 00:13:51,633 --> 00:13:54,633 {\an1}VILLENEUVE (translated): I must have been five 289 00:13:54,666 --> 00:13:56,233 {\an7}or six years old. 290 00:13:56,266 --> 00:13:58,233 {\an7}My parents brought me here one day, 291 00:13:58,266 --> 00:14:00,866 {\an1}like every child from Paris. 292 00:14:00,900 --> 00:14:03,500 I was fascinated by the architecture. 293 00:14:03,533 --> 00:14:06,600 {\an1}It stayed with me since. 294 00:14:06,633 --> 00:14:10,866 NARRATOR: Since 2013, Phillipe has been responsible 295 00:14:10,900 --> 00:14:13,266 {\an1}for conserving Notre Dame. 296 00:14:13,300 --> 00:14:14,776 {\an1}VILLENEUVE (translated): It was the culmination 297 00:14:14,800 --> 00:14:16,066 of a dream. 298 00:14:16,100 --> 00:14:18,600 {\an1}A dream come true. 299 00:14:18,633 --> 00:14:21,433 {\an1}Today that dream has turned into a nightmare. 300 00:14:21,466 --> 00:14:23,133 ♪ 301 00:14:23,166 --> 00:14:27,366 NARRATOR: The stricken cathedral is a giant house of cards. 302 00:14:27,400 --> 00:14:29,133 If the stone vaulting collapses 303 00:14:29,166 --> 00:14:33,700 {\an1}the weight of the buttresseswill push in the 100-foot walls. 304 00:14:33,733 --> 00:14:37,900 {\an1}And Notre Dame will be no more. 305 00:14:37,933 --> 00:14:40,000 {\an8}♪ 306 00:14:40,033 --> 00:14:41,100 {\an8}VILLENEUVE: 307 00:14:42,500 --> 00:14:46,966 NARRATOR: So Phillipe heads up a rapid response team... 308 00:14:47,000 --> 00:14:48,533 {\an1}dozens of engineers, 309 00:14:48,566 --> 00:14:52,200 {\an1}architects, and scientists. 310 00:14:52,233 --> 00:14:54,933 {\an1}Their task is to prevent a total collapse of the cathedral. 311 00:14:54,966 --> 00:14:57,009 {\an1}VILLENEUVE (translated): From the bottom of my heart, 312 00:14:57,033 --> 00:14:59,209 {\an1}I want to thank you all for your dedication, your approach, 313 00:14:59,233 --> 00:15:00,566 your passion. 314 00:15:00,600 --> 00:15:03,333 {\an1}You are doing a very difficult job, which is essential 315 00:15:03,366 --> 00:15:04,500 {\an1}for the cathedral. 316 00:15:05,933 --> 00:15:08,200 NARRATOR: It's not only a difficult job, 317 00:15:08,233 --> 00:15:11,466 {\an1}it's also hazardous. 318 00:15:11,500 --> 00:15:13,800 {\an1}The crumbling stone vaults 319 00:15:13,833 --> 00:15:15,933 {\an1}and twisted scaffolding make any visit 320 00:15:15,966 --> 00:15:19,000 {\an1}inside to investigate the stability of the structure 321 00:15:19,033 --> 00:15:21,933 {\an1}extremely dangerous. 322 00:15:21,966 --> 00:15:24,209 (translated): On the vaults we have the problem of the impact 323 00:15:24,233 --> 00:15:27,533 of the fire, but we will alsohave to evaluate 324 00:15:27,566 --> 00:15:31,100 {\an7}the impact of the water used to put out the fire. 325 00:15:31,133 --> 00:15:35,100 (translated): And we can see from here the inside of... 326 00:15:35,133 --> 00:15:36,833 {\an8}(alarm blaring) 327 00:15:36,866 --> 00:15:37,900 {\an8}LEROUX: Go out. 328 00:15:37,933 --> 00:15:40,133 {\an7}The scaffolding is moving. 329 00:15:40,166 --> 00:15:41,700 {\an8}Scaffolding! 330 00:15:41,733 --> 00:15:43,642 NARRATOR: Motion sensors are installed in the melted jumble 331 00:15:43,666 --> 00:15:45,400 {\an1}of scaffolding overhead. 332 00:15:45,433 --> 00:15:47,666 {\an1}These can be triggered by gusts of wind... 333 00:15:47,700 --> 00:15:51,366 {\an1}a warning before a possible full-scale collapse. 334 00:15:51,400 --> 00:15:56,100 {\an1}(alarm blaring continues) 335 00:15:56,133 --> 00:15:59,433 (translated): It's the alarm, because the scaffolding has moved. 336 00:15:59,466 --> 00:16:02,800 We must leave. 337 00:16:02,833 --> 00:16:07,500 {\an8}NARRATOR: There are evacuations like this each week; necessary, 338 00:16:07,533 --> 00:16:09,600 {\an7}but an impediment to the urgent work 339 00:16:09,633 --> 00:16:11,166 {\an7}of stabilizing the structure. 340 00:16:11,200 --> 00:16:15,033 ♪ 341 00:16:15,066 --> 00:16:19,600 (translated): It's very difficult to juggle all these issues. 342 00:16:19,633 --> 00:16:23,533 {\an1}The problem is that we have to take action very quickly. 343 00:16:23,566 --> 00:16:25,266 {\an1}But we need to consider 344 00:16:25,300 --> 00:16:26,800 {\an1}the reality of this building. 345 00:16:26,833 --> 00:16:30,833 {\an1}It's still in danger of collapse. 346 00:16:30,866 --> 00:16:32,342 {\an7}We are still in the stabilization phase 347 00:16:32,366 --> 00:16:34,766 {\an7}of the cathedral. 348 00:16:34,800 --> 00:16:37,000 NARRATOR: To avert a catastrophic collapse, 349 00:16:37,033 --> 00:16:40,800 {\an7}engineers could builda steel skeleton inside the nave 350 00:16:40,833 --> 00:16:43,666 {\an7}to brace the walls. 351 00:16:43,700 --> 00:16:46,633 {\an1}Then, even if the vaulting caves in, 352 00:16:46,666 --> 00:16:50,333 {\an1}the walls of Notre Dame would stay standing. 353 00:16:50,366 --> 00:16:54,500 {\an1}But it's far too dangerous for workers to erect steelwork 354 00:16:54,533 --> 00:16:57,100 {\an1}beneath the compromised structure. 355 00:16:57,133 --> 00:16:59,900 {\an1}We cannot go under the vaults because we don't know 356 00:16:59,933 --> 00:17:01,566 {\an1}whether they'll fall or not. 357 00:17:01,600 --> 00:17:04,666 NARRATOR: So, instead of bracing the walls from the inside, 358 00:17:04,700 --> 00:17:07,700 {\an1}the team will build timber frames 359 00:17:07,733 --> 00:17:10,566 {\an1}under the buttresses outside. 360 00:17:10,600 --> 00:17:14,733 {\an1}Now, if the vaulting does fall in, the buttresses can't push 361 00:17:14,766 --> 00:17:19,600 {\an1}on the walls, and they won't come tumbling down. 362 00:17:19,633 --> 00:17:22,933 {\an7}PERSON 1 (speaking French): 363 00:17:22,966 --> 00:17:26,700 {\an7}PERSON 2 (speaking French): 364 00:17:27,900 --> 00:17:30,366 {\an1}VILLENEUVE (translated): They are very difficult because 365 00:17:30,400 --> 00:17:32,433 {\an1}no flying buttress is identical to another. 366 00:17:32,466 --> 00:17:35,100 {\an1}They are made to measure. 367 00:17:35,133 --> 00:17:37,333 NARRATOR: Workers at this factory race to cut 368 00:17:37,366 --> 00:17:41,133 {\an1}and assemble around 250 tons of timber 369 00:17:41,166 --> 00:17:44,600 {\an1}to create the massive supports Philippe's team needs 370 00:17:44,633 --> 00:17:47,866 {\an1}to prop up the vaults. 371 00:17:47,900 --> 00:17:49,242 {\an1}It's critical each support fits perfectly 372 00:17:49,266 --> 00:17:50,833 {\an1}beneath each flying buttress 373 00:17:50,866 --> 00:17:52,466 {\an1}to hold its weight. 374 00:17:52,500 --> 00:17:56,900 ♪ 375 00:17:56,933 --> 00:18:00,766 {\an1}Working around and inside this space 376 00:18:00,800 --> 00:18:03,566 {\an1}is a logistical nightmare. 377 00:18:03,600 --> 00:18:07,066 {\an1}210 tons of lead cladding covered the cathedral roof. 378 00:18:07,100 --> 00:18:08,966 {\an1}This was mostly melted during the fire, 379 00:18:09,000 --> 00:18:15,366 {\an1}and now toxic lead dust covers every surface. 380 00:18:15,400 --> 00:18:17,100 {\an1}The worksite is highly contaminated. 381 00:18:17,133 --> 00:18:18,633 {\an1}Until the site is cleaned, 382 00:18:18,666 --> 00:18:21,633 {\an1}team members must wear full protective clothing 383 00:18:21,666 --> 00:18:25,533 to pass into the contaminated zone. 384 00:18:25,566 --> 00:18:26,900 {\an1}When leaving site, 385 00:18:26,933 --> 00:18:29,366 they undress, 386 00:18:29,400 --> 00:18:32,566 {\an1}discard all clothing, 387 00:18:32,600 --> 00:18:33,600 {\an1}carefully wash equipment, 388 00:18:33,633 --> 00:18:36,000 {\an1}then shower themselves. 389 00:18:36,033 --> 00:18:40,166 {\an1}Only then can they go back to the clean area 390 00:18:40,200 --> 00:18:41,833 {\an1}even for a lunch break. 391 00:18:41,866 --> 00:18:44,000 {\an1}(Villeneuve speaking French) 392 00:18:44,033 --> 00:18:47,000 {\an1}VILLENEUVE (translated): It's very difficult to endure for the workers 393 00:18:47,033 --> 00:18:50,466 {\an1}who have had to deal with these procedures for months. 394 00:18:50,500 --> 00:18:53,800 {\an1}These regulations are not normal. 395 00:18:53,833 --> 00:18:58,833 {\an1}But this whole site is not normal. 396 00:18:58,866 --> 00:19:01,166 NARRATOR: But, finally, five months later, 397 00:19:01,200 --> 00:19:04,800 {\an1}all 28 flying buttresses are locked in place 398 00:19:04,833 --> 00:19:07,166 {\an1}and the walls are safe. 399 00:19:07,200 --> 00:19:11,500 {\an1}Now they can turn to the next challenge... 400 00:19:11,533 --> 00:19:13,833 {\an1}secure the melted mass of scaffolding 401 00:19:13,866 --> 00:19:17,066 {\an1}that hangs precariously over the cathedral. 402 00:19:19,366 --> 00:19:21,966 {\an1}The scaffold weighs more than a jumbo jet, 403 00:19:22,000 --> 00:19:27,233 {\an1}and only rests on four spindly legs. 404 00:19:27,266 --> 00:19:31,066 {\an1}The team plans to wrap three massive steel lattice beams 405 00:19:31,100 --> 00:19:35,933 {\an1}around it to tie the fragile upper parts together. 406 00:19:35,966 --> 00:19:39,233 {\an1}Then they'll build more scaffolding either side 407 00:19:39,266 --> 00:19:41,733 {\an1}and lay steel beams across it. 408 00:19:43,600 --> 00:19:47,666 {\an1}That way workers can get inside the stricken scaffolding 409 00:19:47,700 --> 00:19:52,533 {\an1}to help cut off its 50,000 steel poles, 410 00:19:52,566 --> 00:19:57,900 {\an1}a truly Herculean task. 411 00:19:57,933 --> 00:20:00,966 {\an1}Only then can the team put up a temporary roof 412 00:20:01,000 --> 00:20:02,833 {\an1}to protect them from the elements 413 00:20:02,866 --> 00:20:05,833 {\an1}while they rebuild Notre Dame. 414 00:20:05,866 --> 00:20:08,076 {\an1}VILLENEUVE (translated): It's going to be an extremely dangerous operation. 415 00:20:08,100 --> 00:20:09,833 {\an1}The spire has disappeared, 416 00:20:09,866 --> 00:20:12,233 {\an1}but the scaffolding is still there. 417 00:20:12,266 --> 00:20:14,900 It moves a bit, but it's still there. 418 00:20:14,933 --> 00:20:18,533 NARRATOR: While engineers gear up to remove the scaffolding, 419 00:20:18,566 --> 00:20:21,233 {\an1}architect Rémi Fromont 420 00:20:21,266 --> 00:20:22,866 {\an1}and Livio De Luca 421 00:20:22,900 --> 00:20:26,000 {\an1}begin a groundbreaking project that will combine 422 00:20:26,033 --> 00:20:28,866 {\an1}the investigative work with new scientific analysis. 423 00:20:28,900 --> 00:20:34,933 {\an1}Their ambition is to create adata-rich model of Notre Dame... 424 00:20:34,966 --> 00:20:38,100 {\an1}a digital twin. 425 00:20:38,133 --> 00:20:42,500 {\an1}The digital twin will embed not only the geometric structure, 426 00:20:42,533 --> 00:20:46,133 {\an7}or the visual appearance of the cathedral, 427 00:20:46,166 --> 00:20:51,933 {\an7}but also all the scientific data coming from the studies. 428 00:20:51,966 --> 00:20:54,600 {\an1}For example, you can click on a stone in the vault 429 00:20:54,633 --> 00:20:57,033 {\an1}and access to all the information 430 00:20:57,066 --> 00:21:01,066 {\an1}about its physical properties such as the provenance, 431 00:21:01,100 --> 00:21:03,733 {\an1}but also the mechanical behavior 432 00:21:03,766 --> 00:21:06,900 {\an1}within the entire structure. 433 00:21:06,933 --> 00:21:09,700 NARRATOR: Luckily for Livio, a series of highly detailed 434 00:21:09,733 --> 00:21:15,466 {\an1}laser scans of the cathedralhave been conducted since 2006. 435 00:21:15,500 --> 00:21:20,166 {\an1}These are brought together in this priceless 3D dynamic map 436 00:21:20,200 --> 00:21:23,100 {\an1}to show every stone, timber, and iron nail in the structure, 437 00:21:23,133 --> 00:21:28,200 {\an1}across time, from the12th century to the present day. 438 00:21:28,233 --> 00:21:32,733 DE LUCA: This is an unprecedented project. 439 00:21:32,766 --> 00:21:36,266 {\an1}The ambition is to collect all the information from the past, 440 00:21:36,300 --> 00:21:38,033 {\an1}to pass it to the future. 441 00:21:38,066 --> 00:21:41,666 NARRATOR: There's very little first-hand information 442 00:21:41,700 --> 00:21:43,366 {\an1}about the construction of Notre Dame, 443 00:21:43,400 --> 00:21:46,600 {\an1}or the craftspeople who built it. 444 00:21:46,633 --> 00:21:48,266 {\an1}In the wake of the fire, 445 00:21:48,300 --> 00:21:50,566 {\an1}new studies of the cathedral's materials 446 00:21:50,600 --> 00:21:52,933 {\an1}could unlock these secrets. 447 00:21:52,966 --> 00:21:54,900 ♪ 448 00:21:54,933 --> 00:21:57,733 This new data, once included in the digital twin, 449 00:21:57,766 --> 00:22:02,933 {\an1}will provide a blueprint for the restoration and rebuild. 450 00:22:02,966 --> 00:22:05,600 ♪ 451 00:22:05,633 --> 00:22:08,166 {\an1}Inside Notre Dame, 452 00:22:08,200 --> 00:22:13,466 {\an1}scientists begin to gather data and investigate the damage 453 00:22:13,500 --> 00:22:14,600 {\an1}to treasured statues, 454 00:22:14,633 --> 00:22:15,700 murals, 455 00:22:15,733 --> 00:22:17,266 and windows. 456 00:22:20,800 --> 00:22:25,200 {\an1}The cathedral's most fragile wonder, its stained glass, 457 00:22:25,233 --> 00:22:28,433 {\an1}dates back to the 13th century. 458 00:22:28,466 --> 00:22:31,566 {\an1}36 windows circled the lower level, 459 00:22:31,600 --> 00:22:37,633 {\an1}42 around the middle level, and 43 around the upper level. 460 00:22:37,666 --> 00:22:40,333 {\an1}The three famous Rose windows 461 00:22:40,366 --> 00:22:43,366 {\an1}span up to 42 feet in diameter 462 00:22:43,400 --> 00:22:46,666 {\an1}and are made up of over 1,100 panels 463 00:22:46,700 --> 00:22:48,833 {\an1}of beautiful stained glass. 464 00:22:48,866 --> 00:22:52,600 Miraculously, they survive the fire intact. 465 00:22:52,633 --> 00:22:54,833 But the intense heat that melted 466 00:22:54,866 --> 00:22:57,200 {\an8}the cathedral's lead-covered roof 467 00:22:57,233 --> 00:22:59,066 {\an8}means that much of the glasswork 468 00:22:59,100 --> 00:23:03,100 {\an1}is now covered in a layer of toxic lead powder. 469 00:23:03,133 --> 00:23:06,200 {\an1}Removing it could damage the delicate glass 470 00:23:06,233 --> 00:23:10,100 {\an1}and be harmful to restorers. 471 00:23:10,133 --> 00:23:14,200 CLAUDINE LOISEL: It was really painful to see the catastrophe on the TV. 472 00:23:14,233 --> 00:23:18,800 {\an1}I was looking to see what's happen around the windows 473 00:23:18,833 --> 00:23:21,533 {\an1}and it was, of course, totally difficult 474 00:23:21,566 --> 00:23:24,133 {\an1}to have a good idea of what's happened. 475 00:23:24,166 --> 00:23:27,933 {\an7}There is a before and after 15 April, 476 00:23:27,966 --> 00:23:30,666 {\an7}for historical monuments, that's for sure. 477 00:23:30,700 --> 00:23:33,866 NARRATOR: Glass scientist Claudine Loisel 478 00:23:33,900 --> 00:23:36,100 {\an1}uses a handheld digital microscope 479 00:23:36,133 --> 00:23:38,533 {\an1}to investigate the levels of lead powder 480 00:23:38,566 --> 00:23:41,100 {\an1}on the stained glass. 481 00:23:41,133 --> 00:23:43,166 {\an1}She must then formulate a strategy 482 00:23:43,200 --> 00:23:47,133 {\an1}to clean every single panel;a vast decontamination program. 483 00:23:47,166 --> 00:23:50,900 {\an1}This window is in the back of the cathedral, 484 00:23:50,933 --> 00:23:54,500 {\an1}in the lower level, furthest from the inferno. 485 00:23:54,533 --> 00:23:58,900 {\an1}But it's still badly contaminated. 486 00:23:58,933 --> 00:24:00,866 {\an7}(speaking French) 487 00:24:00,900 --> 00:24:04,966 NARRATOR: Fortunately, these windows havenot been cleaned for 100 years, 488 00:24:05,000 --> 00:24:07,833 {\an1}so the lead has settled on top 489 00:24:07,866 --> 00:24:11,733 of a dust layer, not on the glass itself. 490 00:24:11,766 --> 00:24:15,733 The first thick layer of deposit was, we can say 491 00:24:15,766 --> 00:24:17,566 {\an1}has a small protection in one way. 492 00:24:17,600 --> 00:24:21,200 {\an1}So we have just to remove all the deposit, 493 00:24:21,233 --> 00:24:24,600 {\an1}to clean these windows from the 19th century. 494 00:24:24,633 --> 00:24:28,633 NARRATOR: Claudine examines deposits from windows around the cathedral. 495 00:24:28,666 --> 00:24:31,333 {\an1}The samples reveal vital clues 496 00:24:31,366 --> 00:24:33,400 {\an1}about the spread of the lead contamination. 497 00:24:33,433 --> 00:24:35,133 LOISEL: After the spire fell, 498 00:24:35,166 --> 00:24:38,066 {\an1}the cloud of dust, lead, and different particle, 499 00:24:38,100 --> 00:24:41,033 {\an1}push in the other direction, 500 00:24:41,066 --> 00:24:43,133 {\an1}so we are a little bit more protected in this area. 501 00:24:43,166 --> 00:24:48,000 NARRATOR: The windows of the upper level, in the path of the lead cloud, 502 00:24:48,033 --> 00:24:51,500 {\an1}have been most contaminated. 503 00:24:51,533 --> 00:24:54,100 {\an1}The team takes out and transports these panels 504 00:24:54,133 --> 00:24:56,333 {\an1}to this special laboratory 505 00:24:56,366 --> 00:25:01,633 {\an1}where they experiment with ways to remove the lead. 506 00:25:01,666 --> 00:25:05,633 {\an1}First, Claudine uses a precision vacuum cleaner 507 00:25:05,666 --> 00:25:07,600 {\an1}to remove the hundred years of dust 508 00:25:07,633 --> 00:25:09,866 {\an1}and most of the lead powder along with it. 509 00:25:09,900 --> 00:25:16,900 LOISEL: So this is a good way to protect the conservator. 510 00:25:16,933 --> 00:25:21,366 {\an1}You can control the action, the pressure on the glass 511 00:25:21,400 --> 00:25:23,966 {\an1}and also on the painting. 512 00:25:24,000 --> 00:25:25,833 NARRATOR: Then she uses water and cotton balls 513 00:25:25,866 --> 00:25:29,166 to remove the last of the lead. 514 00:25:29,200 --> 00:25:30,866 LOISEL: Of course, 515 00:25:30,900 --> 00:25:33,366 {\an1}you need scientific evidence that it's working. 516 00:25:33,400 --> 00:25:36,400 NARRATOR: Claudine uses x-ray spectroscopy 517 00:25:36,433 --> 00:25:38,700 {\an1}to determine exactly how many wipes it takes 518 00:25:38,733 --> 00:25:42,666 {\an1}to bring the lead down to normal levels. 519 00:25:42,700 --> 00:25:48,600 LOISEL: So we can identify each chemicalelement we have in the material. 520 00:25:48,633 --> 00:25:51,166 NARRATOR: Too few wipes and the lead will remain. 521 00:25:51,200 --> 00:25:56,433 {\an1}Too many wipes and restorationwill take longer than necessary. 522 00:25:56,466 --> 00:25:59,200 LOISEL: Okay, 523 00:25:59,233 --> 00:26:03,233 {\an1}now the analysis is finished. 524 00:26:03,266 --> 00:26:06,566 NARRATOR: After five wipes, Claudine checks to see 525 00:26:06,600 --> 00:26:09,100 if the glass is decontaminated. 526 00:26:09,133 --> 00:26:11,900 ♪ 527 00:26:11,933 --> 00:26:16,400 LOISEL: Okay, we have different chemical element... calcium, iron, 528 00:26:16,433 --> 00:26:20,133 {\an1}and if we want to see the lead... 529 00:26:20,166 --> 00:26:23,066 {\an1}there is no lead! (laughs) 530 00:26:23,100 --> 00:26:25,366 {\an1}After nine months we can see 531 00:26:25,400 --> 00:26:28,633 {\an1}a good solution, a good way to clean and to preserve 532 00:26:28,666 --> 00:26:30,600 {\an1}the stained glass windows from Notre Dame. 533 00:26:30,633 --> 00:26:35,700 ♪ 534 00:26:35,733 --> 00:26:38,500 NARRATOR: The upper level windows were not only in the path 535 00:26:38,533 --> 00:26:39,733 {\an1}of the lead cloud, 536 00:26:39,766 --> 00:26:44,600 {\an1}but also closest to the inferno. 537 00:26:44,633 --> 00:26:47,666 Claudine hunts for hairline cracks 538 00:26:47,700 --> 00:26:50,533 {\an1}caused by thermal shock, 539 00:26:50,566 --> 00:26:53,000 {\an1}the rapid heating and cooling of the glass. 540 00:26:53,033 --> 00:26:56,666 LOISEL: These cracks is due to the fire. 541 00:26:56,700 --> 00:26:58,233 This is a recent cracks 542 00:26:58,266 --> 00:27:00,900 {\an1}and this is typical thermal shock. 543 00:27:00,933 --> 00:27:03,366 NARRATOR: It looks like the upper level stained glass 544 00:27:03,400 --> 00:27:06,533 {\an1}will need to be painstakingly glued back together. 545 00:27:06,566 --> 00:27:11,033 {\an1}But inside Notre Dame, 546 00:27:11,066 --> 00:27:12,533 {\an1}the lower level stained glass appears 547 00:27:12,566 --> 00:27:13,900 {\an1}to have survived unscathed. 548 00:27:13,933 --> 00:27:18,833 LOISEL: And here we can see we have a good stability, 549 00:27:18,866 --> 00:27:22,066 {\an1}adherence of the painting, 550 00:27:22,100 --> 00:27:24,633 {\an1}so there is absolutely no thermal shock, 551 00:27:24,666 --> 00:27:27,433 {\an1}that's good news for us. 552 00:27:27,466 --> 00:27:30,000 NARRATOR: On site, 553 00:27:30,033 --> 00:27:31,766 {\an1}the teams of scientists 554 00:27:31,800 --> 00:27:34,266 {\an1}meet the engineers and architects 555 00:27:34,300 --> 00:27:36,200 {\an1}to share their findings. 556 00:27:36,233 --> 00:27:41,300 {\an7}LOISEL (speaking French): 557 00:27:45,266 --> 00:27:48,033 NARRATOR: Once Claudine's team hasrestored Notre Dame's glasswork 558 00:27:48,066 --> 00:27:51,333 {\an7}to its former glory, they may use 559 00:27:51,366 --> 00:27:53,500 {\an7}a radical new preservation technique 560 00:27:53,533 --> 00:27:55,933 {\an7}to safeguard it for future generations. 561 00:27:58,066 --> 00:28:02,200 {\an7}It's being used on a huge scale here, in northern England. 562 00:28:02,233 --> 00:28:04,433 {\an8}♪ 563 00:28:04,466 --> 00:28:06,600 {\an7}This is York Minster, 564 00:28:06,633 --> 00:28:08,533 {\an7}an 800-year-old Gothic masterpiece 565 00:28:08,566 --> 00:28:13,233 {\an7}and home to the largest expanse of medieval stained glass 566 00:28:13,266 --> 00:28:14,366 {\an8}in the U.K., 567 00:28:14,400 --> 00:28:18,300 {\an7}the Great East Window. 568 00:28:18,333 --> 00:28:20,000 {\an7}It is one of the largest windows ever made 569 00:28:20,033 --> 00:28:21,300 {\an7}anywhere in the medieval world. 570 00:28:21,333 --> 00:28:24,333 {\an1}We've got glass from the 12th right through 571 00:28:24,366 --> 00:28:28,333 {\an1}to the 18th century in quite significant quantities. 572 00:28:28,366 --> 00:28:33,033 {\an7}And it is really our nationaltreasure house of stained glass. 573 00:28:33,066 --> 00:28:34,866 ♪ 574 00:28:34,900 --> 00:28:39,000 NARRATOR: Engineers here are completing a $12 million project 575 00:28:39,033 --> 00:28:42,300 {\an1}to protect York Minster's stained glass 576 00:28:42,333 --> 00:28:46,633 {\an1}from harmful UV rays and the corrosive effects of moisture. 577 00:28:46,666 --> 00:28:48,500 {\an1}In modern stained-glass conservation, 578 00:28:48,533 --> 00:28:51,400 {\an1}we're really doing as much as we can to keep 579 00:28:51,433 --> 00:28:56,033 {\an1}both surfaces of the historic stained glass dry and stable, 580 00:28:56,066 --> 00:28:57,900 {\an1}and that's where our ventilated, 581 00:28:57,933 --> 00:29:01,633 {\an1}environmental protective glazing comes into play. 582 00:29:01,666 --> 00:29:04,000 ♪ 583 00:29:04,033 --> 00:29:06,566 MATT NICKELS: You can see that I'm almost in. 584 00:29:06,600 --> 00:29:08,200 (chuckles) 585 00:29:08,233 --> 00:29:11,566 {\an1}I think it's just this last bit here. 586 00:29:11,600 --> 00:29:15,833 NARRATOR: Matt Nickels is installing this new conservation system. 587 00:29:15,866 --> 00:29:19,633 {\an1}He slots a protective clear glass exterior frame 588 00:29:19,666 --> 00:29:21,500 {\an1}into the window opening. 589 00:29:21,533 --> 00:29:24,733 {\an7}This goes into the original glazing groove, 590 00:29:24,766 --> 00:29:26,833 {\an7}where the medieval glass would have been. 591 00:29:26,866 --> 00:29:31,200 NARRATOR: This protective glazingprevents corrosive condensation 592 00:29:31,233 --> 00:29:34,266 from forming on the 800-year-old stained glass 593 00:29:34,300 --> 00:29:35,766 {\an1}that will sit behind it. 594 00:29:35,800 --> 00:29:38,866 NICKELS: The gap created means that 595 00:29:38,900 --> 00:29:40,276 there's air circulation running through. 596 00:29:40,300 --> 00:29:41,933 {\an1}And when you've got air circulation, 597 00:29:41,966 --> 00:29:43,933 {\an1}it's regulating the temperature, 598 00:29:43,966 --> 00:29:46,500 {\an1}which means that there's less moisture on the glass. 599 00:29:46,533 --> 00:29:53,366 NARRATOR: Each frame is custom made and takes great skill to fit. 600 00:29:53,400 --> 00:29:55,300 NICKELS: You don't want to make it too small 601 00:29:55,333 --> 00:29:56,609 because it's going to obviously slide through. 602 00:29:56,633 --> 00:29:58,933 No two windows are gonna be the same. 603 00:29:58,966 --> 00:30:01,633 NARRATOR: With the outer panel installed, 604 00:30:01,666 --> 00:30:04,566 {\an1}they can reinstate the layer of medieval glass. 605 00:30:06,200 --> 00:30:09,866 NICKELS: They're actually in fairly good condition 606 00:30:09,900 --> 00:30:12,466 {\an1}considering that they're early 13th century. 607 00:30:12,500 --> 00:30:13,900 {\an1}There's always the worry whenever 608 00:30:13,933 --> 00:30:15,666 {\an1}you're handling glass like this, 609 00:30:15,700 --> 00:30:16,709 {\an1}but you just got to make sure 610 00:30:16,733 --> 00:30:18,966 {\an1}that you're really, really careful. 611 00:30:20,666 --> 00:30:21,633 {\an1}There's nothing quite like 612 00:30:21,666 --> 00:30:23,600 {\an1}seeing it with sunlight behind it. 613 00:30:23,633 --> 00:30:26,800 {\an1}When you put it up like this, it's quite magical, isn't it? 614 00:30:26,833 --> 00:30:29,166 ♪ 615 00:30:29,200 --> 00:30:30,766 NARRATOR: Techniques like this 616 00:30:30,800 --> 00:30:34,666 {\an1}offer a glimpse of how scientists like Claudine 617 00:30:34,700 --> 00:30:38,566 {\an1}may eventually preserve Notre Dame's glass. 618 00:30:38,600 --> 00:30:41,766 {\an1}This is the best way to protect stained glass windows, 619 00:30:41,800 --> 00:30:44,866 {\an1}so it will be for sure an option 620 00:30:44,900 --> 00:30:47,633 {\an1}to protect the windows for Notre Dame. 621 00:30:47,666 --> 00:30:50,066 ♪ 622 00:30:50,100 --> 00:30:52,933 NARRATOR: Had the vaulting collapsed 623 00:30:52,966 --> 00:30:54,666 {\an1}next to the windows, 624 00:30:54,700 --> 00:30:57,500 {\an1}the glass could have been badly damaged. 625 00:30:57,533 --> 00:30:59,566 {\an1}But luckily, the stone vaulting, 626 00:30:59,600 --> 00:31:02,800 {\an1}which sits just under the timber and lead roof, 627 00:31:02,833 --> 00:31:05,900 {\an1}protected the windows from the inferno above. 628 00:31:05,933 --> 00:31:08,400 {\an1}VILLENEUVE (translated): When the architects of the Middle Ages 629 00:31:08,433 --> 00:31:10,233 {\an1}constructed this vaulting, 630 00:31:10,266 --> 00:31:13,633 {\an7}they used it to separate the timber frame of the roof 631 00:31:13,666 --> 00:31:15,333 {\an7}from the rest of the cathedral. 632 00:31:15,366 --> 00:31:19,600 {\an7}So the vaulting took the shock of the falling timber 633 00:31:19,633 --> 00:31:22,900 and the fire and the firefighters' water. 634 00:31:22,933 --> 00:31:25,500 ♪ 635 00:31:25,533 --> 00:31:27,542 NARRATOR: The magnificent vaulting was built to be resilient, 636 00:31:27,566 --> 00:31:31,333 {\an1}thanks to precise medieval craftsmanship, 637 00:31:31,366 --> 00:31:36,033 {\an1}using over a thousand cubic yards of limestone. 638 00:31:36,066 --> 00:31:39,566 ♪ 639 00:31:39,600 --> 00:31:42,733 {\an1}The arches work together to support the roof 640 00:31:42,766 --> 00:31:44,933 {\an1}and stabilize the outer walls. 641 00:31:46,800 --> 00:31:49,500 {\an1}But the intense heat from the fire 642 00:31:49,533 --> 00:31:50,600 {\an1}and the collapsing spire 643 00:31:50,633 --> 00:31:53,733 took out 15% of the stone vaulting. 644 00:31:53,766 --> 00:31:55,200 (spire crashes) 645 00:31:56,866 --> 00:32:00,766 ♪ 646 00:32:00,800 --> 00:32:03,166 Today, three 40-foot-wide holes 647 00:32:03,200 --> 00:32:06,300 {\an1}and several smaller gaps mean the vaults could collapse 648 00:32:06,333 --> 00:32:07,900 at any moment. 649 00:32:07,933 --> 00:32:10,266 ♪ 650 00:32:10,300 --> 00:32:14,700 {\an7}The team collects, storesand catalogues the fallen stone 651 00:32:14,733 --> 00:32:17,633 {\an8}in this tent, located alongside the cathedral. 652 00:32:19,600 --> 00:32:21,833 {\an1}They may be able to use some of this stone 653 00:32:21,866 --> 00:32:23,433 {\an1}to reconstruct the vaults. 654 00:32:23,466 --> 00:32:26,733 ♪ 655 00:32:26,766 --> 00:32:30,866 But it's clear they'll also need to source new stone. 656 00:32:30,900 --> 00:32:34,833 {\an1}Notre Dame is made up of many different types of limestone. 657 00:32:34,866 --> 00:32:38,966 {\an1}Medieval masons chose hard limestone for the towers, 658 00:32:39,000 --> 00:32:45,600 {\an1}pillars, and outer walls tobuild tall and hold up the roof. 659 00:32:45,633 --> 00:32:50,733 {\an7}For the sculptures, they chose dense, fine-grained limestone, 660 00:32:50,766 --> 00:32:54,133 {\an7}that can be carved with great detail. 661 00:32:54,166 --> 00:32:58,233 {\an7}And for the vaults they selected softer, more porous limestone 662 00:32:58,266 --> 00:33:01,200 {\an1}that's light but strong. 663 00:33:01,233 --> 00:33:02,966 {\an1}If the team rebuilding the vaults 664 00:33:03,000 --> 00:33:06,433 pick a limestone that is too heavy, 665 00:33:06,466 --> 00:33:09,733 {\an1}the new vaults may not last as long as they should. 666 00:33:12,033 --> 00:33:13,200 {\an1}Geologist Lise Leroux 667 00:33:13,233 --> 00:33:16,566 {\an1}investigates what quarry this stone came from. 668 00:33:16,600 --> 00:33:19,533 {\an8}LISE LEROUX: We have some blocks coming from 669 00:33:19,566 --> 00:33:23,033 {\an7}the collapse of the vault for study. 670 00:33:24,633 --> 00:33:26,642 NARRATOR: This detective work will help the team source 671 00:33:26,666 --> 00:33:30,400 {\an1}replacement stone that sharesidentical mechanical properties. 672 00:33:31,233 --> 00:33:35,033 {\an8}LEROUX: We have to verify. 673 00:33:35,066 --> 00:33:38,333 NARRATOR: The fallen vaulting stone contains a rare micro-fossil 674 00:33:38,366 --> 00:33:41,000 called orbitolites complanatus, 675 00:33:41,033 --> 00:33:43,300 {\an1}a kind of plankton. 676 00:33:43,333 --> 00:33:46,800 {\an1}Fossils like this are found in just one layer of rock. 677 00:33:46,833 --> 00:33:48,833 {\an1}This will make sourcing new stone 678 00:33:48,866 --> 00:33:51,633 {\an1}of the same type even trickier. 679 00:33:51,666 --> 00:33:54,333 {\an1}Can they use this geological fingerprint 680 00:33:54,366 --> 00:33:58,233 {\an1}to discover the original source of the vaulting stone? 681 00:33:58,266 --> 00:34:00,200 {\an7}LEROUX (speaking French): 682 00:34:00,233 --> 00:34:03,766 NARRATOR: To find out, Lise and fellow Notre Dame scientist 683 00:34:03,800 --> 00:34:08,600 {\an1}Claudine Loisel venture deep beneath Paris. 684 00:34:08,633 --> 00:34:14,600 {\an1}Hidden under the city streets is a rich source of limestone, 685 00:34:14,633 --> 00:34:18,566 {\an1}a vast labyrinth of quarry tunnels. 686 00:34:18,600 --> 00:34:21,266 {\an1}Lise and Claudine enter this maze 687 00:34:21,300 --> 00:34:26,733 {\an1}two miles south of Notre Dame in the famous Catacombs. 688 00:34:26,766 --> 00:34:28,566 {\an1}Oh! 689 00:34:28,600 --> 00:34:32,366 {\an7}(speaking French) 690 00:34:32,400 --> 00:34:33,933 {\an7}LEROUX (speaking French): 691 00:34:37,000 --> 00:34:38,566 {\an7}LOISEL (speaking French): 692 00:34:42,800 --> 00:34:45,966 {\an7}LEROUX (speaking French): 693 00:34:48,733 --> 00:34:50,566 DANY SANDRON: In the late 18th century, 694 00:34:50,600 --> 00:34:54,766 {\an1}the quarries were given a different purpose 695 00:34:54,800 --> 00:34:59,333 {\an7}and they housed bones from old cemeteries, 696 00:34:59,366 --> 00:35:03,933 {\an7}which were inside the towns. 697 00:35:03,966 --> 00:35:06,533 {\an7}Cemeteries which were closed at the end of the 18th century 698 00:35:06,566 --> 00:35:08,200 {\an1}for sanitary reasons. 699 00:35:08,233 --> 00:35:12,533 NARRATOR: Among the bones, 700 00:35:12,566 --> 00:35:15,900 {\an1}Lise and Claudine find traces left by the medieval miners. 701 00:35:15,933 --> 00:35:17,842 LEROUX (translated): Here, the block's been removed 702 00:35:17,866 --> 00:35:21,200 and we're left with this trace. 703 00:35:21,233 --> 00:35:23,466 They then square off the sides, 704 00:35:23,500 --> 00:35:26,433 and use it to build Notre Dame. 705 00:35:28,033 --> 00:35:32,866 {\an1}And the strata height here, itdictates the height of the block 706 00:35:32,900 --> 00:35:35,666 {\an1}that can be extracted. 707 00:35:35,700 --> 00:35:38,433 {\an1}The blocks we see at Notre Dame have this height. 708 00:35:38,466 --> 00:35:41,900 {\an7}So the quarry itself puts a constraint 709 00:35:41,933 --> 00:35:44,266 {\an1}on the construction of Notre Dame. 710 00:35:44,300 --> 00:35:45,842 {\an1}LOISEL (translated): We have life and we have death. 711 00:35:45,866 --> 00:35:47,266 {\an1}LEROUX (translated): Well, yes. 712 00:35:47,300 --> 00:35:49,133 NARRATOR: The upper level of the quarry 713 00:35:49,166 --> 00:35:51,200 {\an1}holds hard limestone with 714 00:35:51,233 --> 00:35:53,566 {\an1}large, well-preserved fossils. 715 00:35:53,600 --> 00:35:54,966 {\an8}LEROUX: These fossils are 716 00:35:55,000 --> 00:35:59,800 {\an7}more characteristic of the limestones 717 00:35:59,833 --> 00:36:04,333 {\an7}used for the pillars, the arch in Notre Dame. 718 00:36:04,366 --> 00:36:05,433 {\an7}But not for the vault. 719 00:36:05,466 --> 00:36:08,633 NARRATOR: Lise and Claudine hope to find 720 00:36:08,666 --> 00:36:11,533 a match for the soft vaulting stone 721 00:36:11,566 --> 00:36:13,366 {\an1}in the lower level of the quarry. 722 00:36:15,000 --> 00:36:18,200 {\an7}Now to look if we can find 723 00:36:18,233 --> 00:36:21,466 {\an7}the specific micro-fossils. 724 00:36:25,066 --> 00:36:30,166 {\an7}I'm not sure, because the surface is very rough 725 00:36:30,200 --> 00:36:34,733 {\an7}and it's not so clear because ofall of the state of the surface. 726 00:36:34,766 --> 00:36:38,400 NARRATOR: The limestone here is softer, 727 00:36:38,433 --> 00:36:40,700 {\an1}but Lise cannot see a match for the rare micro-fossil 728 00:36:40,733 --> 00:36:43,366 {\an1}found in the Notre Dame vaulting sample. 729 00:36:44,933 --> 00:36:47,266 ♪ 730 00:36:47,300 --> 00:36:49,666 {\an1}So, back in the lab, 731 00:36:49,700 --> 00:36:52,800 {\an1}she takes a closer look at a sample of limestone 732 00:36:52,833 --> 00:36:55,133 {\an1}from the lower level of the quarry. 733 00:36:56,066 --> 00:36:58,900 {\an7}These little fossils... 734 00:36:58,933 --> 00:37:00,200 {\an7}this one, this one, 735 00:37:00,233 --> 00:37:02,300 {\an8}this one... 736 00:37:02,333 --> 00:37:06,100 {\an8}are, in fact some planktonic fossils, 737 00:37:06,133 --> 00:37:08,366 {\an7}which are called foraminifera. 738 00:37:08,400 --> 00:37:13,400 NARRATOR: It's not the fossil signature she's looking for. 739 00:37:13,433 --> 00:37:16,233 But then... 740 00:37:16,266 --> 00:37:18,100 {\an8}Oh! 741 00:37:19,700 --> 00:37:25,233 {\an8}This one here is orbitolites complanatus. 742 00:37:25,266 --> 00:37:30,733 {\an7}This little planktonic fossil is a dating fossil, 743 00:37:30,766 --> 00:37:36,500 {\an7}which match with the stone coming from the vault. 744 00:37:36,533 --> 00:37:38,900 {\an7}It's a stratigraphic indicator, 745 00:37:38,933 --> 00:37:42,566 {\an7}characteristic from the Middle Lutetian, 746 00:37:42,600 --> 00:37:46,166 {\an7}which is a geological age of deposit. 747 00:37:46,200 --> 00:37:52,233 NARRATOR: Lise confirms the origin of the Notre Dame vaulting stone. 748 00:37:52,266 --> 00:37:54,066 It's quarried from the deepest seams 749 00:37:54,100 --> 00:37:55,766 {\an1}of limestone beneath Paris. 750 00:37:55,800 --> 00:37:57,566 {\an8}Conclusive. 751 00:37:57,600 --> 00:37:59,733 NARRATOR: But what about the harder limestone, 752 00:37:59,766 --> 00:38:01,966 {\an1}used by medieval masons to build 753 00:38:02,000 --> 00:38:05,333 Notre Dame'sload-bearing pillars and arches? 754 00:38:05,366 --> 00:38:08,800 {\an7}Another micro fossil signature confirms the origin 755 00:38:08,833 --> 00:38:10,400 {\an7}of this type as well. 756 00:38:10,433 --> 00:38:14,700 {\an8}LEROUX: The arches are built with a hard stone... 757 00:38:14,733 --> 00:38:17,700 {\an7}with a resistant stone, to support the vault. 758 00:38:17,733 --> 00:38:19,400 {\an7}And the vault itself 759 00:38:19,433 --> 00:38:21,933 {\an7}is logically constructed 760 00:38:21,966 --> 00:38:25,166 {\an8}with a lighter, more porous stone. 761 00:38:25,200 --> 00:38:29,266 {\an7}And in the quarry located in Paris, 762 00:38:29,300 --> 00:38:30,800 {\an7}we have this two kind of stone. 763 00:38:30,833 --> 00:38:34,700 NARRATOR: Medieval masons knew exactly how to exploit 764 00:38:34,733 --> 00:38:36,533 the varying mechanical properties 765 00:38:36,566 --> 00:38:37,776 of the limestone for Notre Dame; 766 00:38:37,800 --> 00:38:42,866 {\an1}knowledge passed down through the generations. 767 00:38:42,900 --> 00:38:46,500 {\an7}Sourcing more of the correct stone won't be easy... 768 00:38:46,533 --> 00:38:49,600 {\an8}the old quarries are no longer active. 769 00:38:49,633 --> 00:38:51,000 {\an7}But engineers now know 770 00:38:51,033 --> 00:38:53,100 {\an1}what limestone to look for... 771 00:38:53,133 --> 00:38:57,533 {\an1}this will help them find a match in quarries outside Paris. 772 00:39:01,533 --> 00:39:04,200 Stone is not the only raw material 773 00:39:04,233 --> 00:39:05,866 {\an1}that will need to be replaced 774 00:39:05,900 --> 00:39:07,733 {\an1}as engineers reconstruct Notre Dame. 775 00:39:07,766 --> 00:39:13,100 The timber roof was also a medieval wonder. 776 00:39:13,133 --> 00:39:18,566 {\an1}It was constructed from 25,000 cubic feet of timber, 777 00:39:18,600 --> 00:39:20,766 {\an1}cut from 52 acres of oak... 778 00:39:20,800 --> 00:39:24,533 {\an1}that's approximately 1,300 trees. 779 00:39:24,566 --> 00:39:28,466 For this reason, it was known as "the forest." 780 00:39:28,500 --> 00:39:31,566 Every single oak in Notre Dame's forest 781 00:39:31,600 --> 00:39:34,500 {\an1}was handpicked for the physical properties needed 782 00:39:34,533 --> 00:39:36,766 {\an1}in the roof structure... 783 00:39:36,800 --> 00:39:38,833 {\an1}from dense straight oak for pillars, 784 00:39:38,866 --> 00:39:42,400 to curved oak for support arches. 785 00:39:42,433 --> 00:39:45,533 (wood cracking) 786 00:39:45,566 --> 00:39:50,033 {\an1}But the fire burned every beam in the forest. 787 00:39:50,066 --> 00:39:56,266 {\an1}Today, this intricate 550-ton timber jigsaw lies in ruins. 788 00:40:02,100 --> 00:40:05,900 {\an1}LAVIER (translated): We thought this sublime roof would be here forever. 789 00:40:05,933 --> 00:40:07,866 {\an1}It was a big puzzle with beams 790 00:40:07,900 --> 00:40:09,466 {\an7}from different periods, 791 00:40:09,500 --> 00:40:11,200 {\an8}all the way back to the 13th century. 792 00:40:11,233 --> 00:40:12,533 {\an7}And to see it suddenly 793 00:40:12,566 --> 00:40:14,766 {\an1}all burned, all mixed up... 794 00:40:14,800 --> 00:40:17,833 {\an1}Oh, it's very emotional. 795 00:40:17,866 --> 00:40:19,466 {\an1}It's very difficult. 796 00:40:19,500 --> 00:40:23,066 NARRATOR: Almost 60 tons of the precious roof timber 797 00:40:23,100 --> 00:40:26,866 {\an1}still lie precariously on top of the vaults. 798 00:40:26,900 --> 00:40:28,666 {\an1}Despite the destruction, 799 00:40:28,700 --> 00:40:31,300 {\an1}every single beam holds the history of Notre Dame. 800 00:40:31,333 --> 00:40:35,366 It has deep archaeological value. 801 00:40:35,400 --> 00:40:38,000 {\an1}It's vital that workers forensically record 802 00:40:38,033 --> 00:40:40,400 the position where each beam fell, 803 00:40:40,433 --> 00:40:42,466 {\an1}before they remove them. 804 00:40:42,500 --> 00:40:43,766 {\an1}This helps them determine 805 00:40:43,800 --> 00:40:46,033 {\an1}where it originally sat in the roof structure. 806 00:40:47,900 --> 00:40:50,866 {\an1}Now, these highly trained rope access technicians 807 00:40:50,900 --> 00:40:53,666 gear up to catalogue and clear 808 00:40:53,700 --> 00:40:55,466 {\an1}the charred timber on the vaults. 809 00:40:56,933 --> 00:40:59,966 {\an7}BOTH (speaking French): 810 00:41:01,266 --> 00:41:03,233 {\an7}It's not possible to walk on the vaults, 811 00:41:03,266 --> 00:41:05,900 {\an1}because the structure is very precarious. 812 00:41:05,933 --> 00:41:07,000 They needed to 813 00:41:07,033 --> 00:41:10,933 create a way to access with ropes. 814 00:41:12,633 --> 00:41:14,300 {\an1}We need to wear a special mask 815 00:41:14,333 --> 00:41:17,966 {\an1}because of the lead dust that we might inhale. 816 00:41:21,333 --> 00:41:24,333 {\an1}We label the timbers 817 00:41:24,366 --> 00:41:25,566 {\an1}and we mark them with a code 818 00:41:25,600 --> 00:41:27,900 {\an1}that the architects will 819 00:41:27,933 --> 00:41:29,566 {\an1}be able to identify. 820 00:41:29,600 --> 00:41:32,966 {\an7}(speaking French): 821 00:41:34,133 --> 00:41:36,300 NARRATOR: The team has their work cut out... 822 00:41:36,333 --> 00:41:38,666 {\an1}there are thousands of separate pieces 823 00:41:38,700 --> 00:41:40,600 {\an1}of timber to catalog. 824 00:41:40,633 --> 00:41:42,833 DE GUILLEBON: We are working day and night. 825 00:41:42,866 --> 00:41:44,233 {\an1}We have a lot of work to do. 826 00:41:49,666 --> 00:41:51,633 NARRATOR: They've already extracted 827 00:41:51,666 --> 00:41:54,866 {\an1}around 4,000 pieces. 828 00:41:54,900 --> 00:41:58,433 Timber scientist Catherine Lavier 829 00:41:58,466 --> 00:42:01,000 {\an1}begins painstaking detective work to reveal 830 00:42:01,033 --> 00:42:03,433 {\an1}how Notre Dame's vast forest 831 00:42:03,466 --> 00:42:05,400 {\an1}was originally assembled 832 00:42:05,433 --> 00:42:08,400 {\an1}and could be rebuilt today. 833 00:42:08,433 --> 00:42:11,800 {\an8}LAVIER: Some pieces were very well-preserved 834 00:42:11,833 --> 00:42:16,300 {\an7}because as you see here, with different faces 835 00:42:16,333 --> 00:42:19,533 {\an7}and another piece of wood is coming here, 836 00:42:19,566 --> 00:42:22,866 {\an7}with a wooden joint here to assemble them. 837 00:42:22,900 --> 00:42:26,366 {\an7}And it's rather typical from the medieval period. 838 00:42:26,400 --> 00:42:29,833 {\an8}And here, 839 00:42:29,866 --> 00:42:33,066 {\an8}you have a mark, 840 00:42:33,100 --> 00:42:34,633 {\an8}of carpenters. 841 00:42:34,666 --> 00:42:38,700 {\an8}So they are sure that this piece with this piece are together. 842 00:42:40,066 --> 00:42:41,600 {\an7}It's very important for carpenters. 843 00:42:41,633 --> 00:42:43,800 {\an8}They prepare the wood on the ground 844 00:42:43,833 --> 00:42:45,366 {\an8}and after that, 845 00:42:45,400 --> 00:42:49,133 {\an7}they go to the roof and reassemble again. 846 00:42:50,066 --> 00:42:53,333 {\an8}Every carpenter has his own way to mark, 847 00:42:53,366 --> 00:42:55,100 {\an7}but in general it's based on 848 00:42:55,133 --> 00:42:59,266 {\an7}the Roman numbers, 849 00:42:59,300 --> 00:43:03,200 {\an7}but we can find some differences between teams of carpenters. 850 00:43:05,133 --> 00:43:06,666 {\an7}We were very surprised to find that 851 00:43:06,700 --> 00:43:09,633 {\an7}because I thought everything will be destroyed. 852 00:43:10,333 --> 00:43:12,633 {\an7}And, finally, not. 853 00:43:12,666 --> 00:43:17,533 NARRATOR: The tree rings of the timbers conceal further clues. 854 00:43:17,566 --> 00:43:20,866 {\an1}Each ring represents one year of growth; 855 00:43:20,900 --> 00:43:22,466 {\an1}a time capsule of information 856 00:43:22,500 --> 00:43:27,133 {\an1}about the life of the tree in that year. 857 00:43:27,166 --> 00:43:32,133 {\an1}Catherine analyzes core samplesfrom Notre Dame's roof trusses. 858 00:43:32,166 --> 00:43:35,833 {\an1}She measures each ring to reveal the secret story 859 00:43:35,866 --> 00:43:37,400 {\an8}of some of the original oak trees 860 00:43:37,433 --> 00:43:38,733 {\an1}the structure was made from. 861 00:43:38,766 --> 00:43:41,666 (translated): This screen shows the size 862 00:43:41,700 --> 00:43:44,066 {\an1}of each ring I measured. 863 00:43:44,100 --> 00:43:45,566 {\an1}At the start of its life, 864 00:43:45,600 --> 00:43:47,366 you see it has very, very large rings, 865 00:43:47,400 --> 00:43:52,966 which correspond to very rapid growth. 866 00:43:53,000 --> 00:43:54,276 {\an1}Next, it looks like it experienced 867 00:43:54,300 --> 00:43:55,700 {\an1}some more dramatic events, 868 00:43:55,733 --> 00:43:57,533 {\an1}some difficult years, 869 00:43:57,566 --> 00:43:59,733 {\an1}here, when the rings are very thin, 870 00:43:59,766 --> 00:44:00,976 {\an1}This could be because of too much rain, 871 00:44:01,000 --> 00:44:04,333 not enough sun, and not enough nutrients. 872 00:44:04,366 --> 00:44:05,609 And then, the life of the tree continues 873 00:44:05,633 --> 00:44:09,800 {\an1}until it's cut down, around its 96th year. 874 00:44:09,833 --> 00:44:12,600 NARRATOR: Catherine is gaining new insight 875 00:44:12,633 --> 00:44:15,600 {\an1}into the types of trees best suited to rebuild 876 00:44:15,633 --> 00:44:18,800 {\an1}the complex forest of Notre Dame. 877 00:44:18,833 --> 00:44:21,400 {\an1}This extraordinary challenge will require 878 00:44:21,433 --> 00:44:24,366 {\an1}around 1,300 oak trees, 879 00:44:24,400 --> 00:44:25,766 {\an1}craftspeople versed in the lost art 880 00:44:25,800 --> 00:44:29,666 {\an1}of medieval carpentry practices, 881 00:44:29,700 --> 00:44:32,200 {\an1}and a blueprint for possibly the most geometrically complex 882 00:44:32,233 --> 00:44:34,466 {\an1}timber structures in Europe. 883 00:44:34,500 --> 00:44:37,333 {\an1}The one person who can unlock 884 00:44:37,366 --> 00:44:39,800 {\an1}the lost forest's geometrical secrets 885 00:44:39,833 --> 00:44:42,733 {\an1}is architect Rémi Fromont. 886 00:44:42,766 --> 00:44:47,300 In 2014, Rémi spent the entire year 887 00:44:47,333 --> 00:44:50,033 {\an1}mapping every inch of the timber. 888 00:44:50,066 --> 00:44:52,233 {\an8}(translated): It was a magical place 889 00:44:52,266 --> 00:44:54,366 {\an8}to go in there; there was a smell. 890 00:44:54,400 --> 00:44:57,400 {\an1}There was a very special atmosphere of light. 891 00:44:57,433 --> 00:45:00,366 {\an1}We still had the traces of tools also on the woods. 892 00:45:00,400 --> 00:45:03,633 {\an1}It sometimes seemed like they only left yesterday. 893 00:45:03,666 --> 00:45:06,066 {\an7}We are collecting photographs, 894 00:45:06,100 --> 00:45:09,333 {\an8}3D point clouds, 895 00:45:09,366 --> 00:45:11,700 {\an8}and the physical and chemical characterization 896 00:45:11,733 --> 00:45:13,200 {\an7}of all the materials. 897 00:45:13,233 --> 00:45:15,966 NARRATOR: The fire at Notre Dame 898 00:45:16,000 --> 00:45:18,500 {\an1}triggers a race across France 899 00:45:18,533 --> 00:45:24,266 {\an1}to 3D scan historical monuments, inside and out. 900 00:45:24,300 --> 00:45:26,900 {\an8}These represent a digital insurance policy 901 00:45:26,933 --> 00:45:28,566 {\an1}to preserve French heritage. 902 00:45:28,600 --> 00:45:31,833 ♪ 903 00:45:31,866 --> 00:45:34,566 {\an1}The laser bounces off each contour in the room. 904 00:45:34,600 --> 00:45:36,300 {\an1}The machine then measures 905 00:45:36,333 --> 00:45:38,100 {\an1}the time it takes for the laser to return. 906 00:45:38,133 --> 00:45:40,766 {\an1}Millions of measurements 907 00:45:40,800 --> 00:45:42,200 {\an1}form a cloud of data 908 00:45:42,233 --> 00:45:44,166 {\an1}called a "point cloud." 909 00:45:44,200 --> 00:45:46,133 ♪ 910 00:45:46,166 --> 00:45:50,700 {\an1}In 2016, researchers used this same technology 911 00:45:50,733 --> 00:45:52,233 {\an1}to create a full point cloud 912 00:45:52,266 --> 00:45:55,266 of Notre Dame's lost timber roof structure. 913 00:45:55,300 --> 00:46:01,033 {\an1}This remarkable 3D scan willcombine with Rémi's 2014 survey, 914 00:46:01,066 --> 00:46:05,333 {\an1}in Livio's digital twin for Notre Dame. 915 00:46:05,366 --> 00:46:06,900 DE LUCA: What we are producing today 916 00:46:06,933 --> 00:46:10,233 {\an8}will be probably the information useful 917 00:46:10,266 --> 00:46:11,500 {\an7}for the next generations. 918 00:46:11,533 --> 00:46:15,233 NARRATOR: The team now has the data they need 919 00:46:15,266 --> 00:46:19,133 {\an1}to rebuild the timber roof with the exact same geometry. 920 00:46:19,166 --> 00:46:20,900 {\an7}The new oak needed 921 00:46:20,933 --> 00:46:24,033 {\an8}could come from forests like this. 922 00:46:24,066 --> 00:46:25,433 {\an7}Almost a third of France 923 00:46:25,466 --> 00:46:28,533 {\an1}is covered with forest. 924 00:46:28,566 --> 00:46:29,809 Oak is a vital strategic resource 925 00:46:29,833 --> 00:46:32,900 throughout theMiddle Ages and the Renaissance. 926 00:46:32,933 --> 00:46:36,533 {\an1}Vast forests are needed tobuild cities and expand navies. 927 00:46:39,233 --> 00:46:41,866 {\an7}This is the Château de Beaumesnil in Normandy. 928 00:46:41,900 --> 00:46:45,200 {\an8}It's a National Historic Monument, 929 00:46:45,233 --> 00:46:46,266 {\an1}built on the site of 930 00:46:46,300 --> 00:46:49,566 {\an1}an 1,100-year-old castle. 931 00:46:49,600 --> 00:46:51,933 {\an1}REÉMY DESMONTS (translated): It was built in seven years. 932 00:46:51,966 --> 00:46:55,100 {\an7}It's something extraordinary for just seven years' work. 933 00:46:55,133 --> 00:46:57,866 NARRATOR: The château has seen better days. 934 00:46:57,900 --> 00:47:01,500 The curved beams that hold up the roof 935 00:47:01,533 --> 00:47:04,600 {\an1}are close to collapse and must be replaced. 936 00:47:07,866 --> 00:47:11,666 {\an8}(translated): The wood grain has been cut through. 937 00:47:11,700 --> 00:47:14,466 {\an1}This weakens the support beam. 938 00:47:14,500 --> 00:47:19,233 {\an1}And then you see that the beam is completely eaten away. 939 00:47:19,266 --> 00:47:23,300 {\an1}The wood is degraded, eaten by the fungus. 940 00:47:25,933 --> 00:47:27,666 NARRATOR: The restoration work here 941 00:47:27,700 --> 00:47:30,633 requires much of the same skill and knowledge 942 00:47:30,666 --> 00:47:33,900 {\an1}it will take to rebuild Notre Dame's lost forest. 943 00:47:35,966 --> 00:47:38,600 {\an1}The timber has been chosen so the curve of the grain 944 00:47:38,633 --> 00:47:42,166 {\an1}perfectly matches the curve of the new beam. 945 00:47:42,200 --> 00:47:43,709 LEO ROUSSEAU: If you get a straight tree, 946 00:47:43,733 --> 00:47:47,166 {\an7}which has a straight grain, and... 947 00:47:47,200 --> 00:47:53,500 {\an1}if you cut a curved piece, piece of wood inside of this, 948 00:47:53,533 --> 00:47:56,900 {\an1}so here is the fiber, so it can break, right there. 949 00:47:56,933 --> 00:48:01,500 But if you take the tree that's curved, 950 00:48:01,533 --> 00:48:04,633 {\an1}the fiber is like this. 951 00:48:04,666 --> 00:48:06,166 {\an1}So it cannot break. 952 00:48:06,200 --> 00:48:09,400 {\an1}You keep all of thestructural strength of the tree. 953 00:48:13,600 --> 00:48:15,166 NARRATOR: The carpenters use 954 00:48:15,200 --> 00:48:17,633 {\an1}an original beam as a template 955 00:48:17,666 --> 00:48:19,966 {\an1}to mark out the new beam on the oak. 956 00:48:20,000 --> 00:48:22,033 {\an7}(speaking French): 957 00:48:23,400 --> 00:48:25,076 NARRATOR: The carpenters who built Notre Dame 958 00:48:25,100 --> 00:48:26,642 {\an1}would be familiar with the tools this team uses 959 00:48:26,666 --> 00:48:28,133 {\an1}to hew the raw timber. 960 00:48:28,166 --> 00:48:31,533 (chopping) 961 00:48:31,566 --> 00:48:34,366 ROSSEAU: So after you split most of the wood, 962 00:48:34,400 --> 00:48:37,766 {\an1}you use a broad-axe. 963 00:48:37,800 --> 00:48:39,400 {\an1}They have a single bevel, 964 00:48:39,433 --> 00:48:44,300 {\an1}long cutting edge, and the handle is offset. 965 00:48:44,333 --> 00:48:46,300 So... 966 00:48:46,333 --> 00:48:48,933 {\an1}if you're working, 967 00:48:48,966 --> 00:48:51,966 as you go down, your hand here, 968 00:48:52,000 --> 00:48:55,233 you see I'm not hitting this sharp edge. 969 00:48:55,266 --> 00:48:58,666 {\an1}(echoing chopping) 970 00:48:58,700 --> 00:49:00,333 {\an8}NARRATOR: For skilled carpenters, 971 00:49:00,366 --> 00:49:02,076 {\an7}cutting Notre Dame's roof timbers with axes, 972 00:49:02,100 --> 00:49:04,366 {\an1}compared to a modern sawmill, 973 00:49:04,400 --> 00:49:07,200 {\an1}will take roughly twice the time; 974 00:49:07,233 --> 00:49:09,500 {\an1}possibly too long. 975 00:49:09,533 --> 00:49:11,933 {\an1}This curved oak will be 976 00:49:11,966 --> 00:49:14,166 {\an1}one of ten the team needs to install 977 00:49:14,200 --> 00:49:17,566 as part of the château roof restoration. 978 00:49:17,600 --> 00:49:21,733 {\an1}It sits alongside this 400-year-old original beam. 979 00:49:21,766 --> 00:49:23,500 {\an1}DESMONTS (translated): This one was cut 980 00:49:23,533 --> 00:49:27,833 {\an1}probably 1635, '37, 981 00:49:27,866 --> 00:49:30,066 {\an1}and then this one 2020. 982 00:49:30,100 --> 00:49:35,400 {\an1}I hope our ancestors are happy with this. 983 00:49:35,433 --> 00:49:37,866 {\an8}NARRATOR: Just like the Notre Dame beams, 984 00:49:37,900 --> 00:49:40,300 {\an8}the Château's original beam holds 985 00:49:40,333 --> 00:49:43,666 {\an8}messages from the old carpenters. 986 00:49:43,700 --> 00:49:47,366 {\an1}DESMONTS (translated): It's extraordinary to find all these marks. 987 00:49:47,400 --> 00:49:49,033 It's very old and at the same time, 988 00:49:49,066 --> 00:49:51,300 it looks like it was done yesterday. 989 00:49:51,333 --> 00:49:53,600 NARRATOR: French craftspeople 990 00:49:53,633 --> 00:49:55,500 have the oak, 991 00:49:55,533 --> 00:49:59,733 {\an7}they have the skills, and they have the plans required 992 00:49:59,766 --> 00:50:03,566 {\an1}to reconstruct Notre Dame's vast forest of roof timbers. 993 00:50:03,600 --> 00:50:07,966 {\an1}It's over a year since the fire ravaged Notre Dame cathedral, 994 00:50:08,000 --> 00:50:11,300 {\an7}and the investigators have not pinpointed 995 00:50:11,333 --> 00:50:12,566 {\an1}the cause of the blaze. 996 00:50:12,600 --> 00:50:16,700 {\an1}Immense challenges and uncertainties still lie ahead. 997 00:50:16,733 --> 00:50:21,500 The building is not yet out of danger. 998 00:50:21,533 --> 00:50:23,100 {\an1}Over the next 12 months, 999 00:50:23,133 --> 00:50:25,700 {\an1}engineers must remove the melted scaffolding 1000 00:50:25,733 --> 00:50:29,166 {\an1}and seal the cathedral roof to make it watertight, 1001 00:50:29,200 --> 00:50:32,466 then stabilize the weakened vaulting. 1002 00:50:32,500 --> 00:50:34,866 {\an1}It's a monumental task. 1003 00:50:34,900 --> 00:50:37,066 And rebuilding the entire cathedral 1004 00:50:37,100 --> 00:50:39,066 {\an1}could take much longer than 1005 00:50:39,100 --> 00:50:42,700 {\an1}the five years decreed by President Macron. 1006 00:50:42,733 --> 00:50:45,033 (translated): Faced with such a drama, 1007 00:50:45,066 --> 00:50:46,433 {\an1}thankfully there's hope. 1008 00:50:48,400 --> 00:50:51,233 {\an1}FROMONT (translated): We need faith for this project. 1009 00:50:51,266 --> 00:50:54,433 {\an1}It's this building itself that generates this faith... 1010 00:50:54,466 --> 00:50:58,466 {\an1}even for atheists... And that's something magical. 1011 00:50:58,500 --> 00:50:59,966 ♪ 1012 00:51:00,000 --> 00:51:02,166 NARRATOR: Architects around the world 1013 00:51:02,200 --> 00:51:03,833 have unleashed their imaginations 1014 00:51:03,866 --> 00:51:08,666 {\an1}to submit grand plans for what the new spire above Notre Dame 1015 00:51:08,700 --> 00:51:09,933 {\an1}could look like... 1016 00:51:09,966 --> 00:51:14,266 {\an1}from mirrored roofs with kaleidoscopic pinnacles, 1017 00:51:14,300 --> 00:51:17,766 {\an1}and vast solar panels powering nearby buildings, 1018 00:51:17,800 --> 00:51:23,600 {\an1}to stained glass edifices thatwill light up the Paris skyline. 1019 00:51:23,633 --> 00:51:25,500 {\an1}However Notre Dame is rebuilt, 1020 00:51:25,533 --> 00:51:29,633 {\an1}the unique collaboration of architects and scientists 1021 00:51:29,666 --> 00:51:30,966 {\an1}is rewriting how we understand 1022 00:51:31,000 --> 00:51:34,866 {\an1}the very fabric of this magnificent cathedral. 1023 00:51:34,900 --> 00:51:36,766 DICKAS: I think the fire in some ways 1024 00:51:36,800 --> 00:51:38,633 {\an1}helped remind a lot of people 1025 00:51:38,666 --> 00:51:40,966 {\an1}what an important part of our sort of shared history 1026 00:51:41,000 --> 00:51:42,966 {\an1}and shared culture this is. 1027 00:51:43,000 --> 00:51:46,300 NARRATOR: Soon, a complete digital twin of Notre Dame 1028 00:51:46,333 --> 00:51:49,466 should allow future generations of craftspeople 1029 00:51:49,500 --> 00:51:54,833 {\an1}to maintain, protect, and faithfully rebuild Notre Dame, 1030 00:51:54,866 --> 00:51:58,433 {\an1}preserving this world treasure for all time. 1031 00:51:58,466 --> 00:52:00,566 (translated): I have only one obsession... 1032 00:52:00,600 --> 00:52:02,666 {\an1}save the cathedral, resurrect it, 1033 00:52:02,700 --> 00:52:04,400 {\an1}and reopen it to the public. 1034 00:52:04,433 --> 00:52:10,266 ♪ 1035 00:52:48,133 --> 00:52:52,466 ♪ 1036 00:53:03,633 --> 00:53:05,733 {\an7}To order this program on DVD, 1037 00:53:05,766 --> 00:53:10,833 {\an8}visit ShopPBS or call 1-800-PLAY-PBS. 1038 00:53:10,866 --> 00:53:13,800 {\an8}Episodes of "NOVA" are available with Passport. 1039 00:53:13,833 --> 00:53:17,933 {\an7}"NOVA" is also available on Amazon Prime Video. 1040 00:53:17,966 --> 00:53:22,000 {\an8}♪ 1041 00:53:30,433 --> 00:53:34,333 {\an8}♪