The fire that gutted the roof of Notre-Dame devastated the cathedral, causing many to fear for the future of the world heritage site. But despite the huge losses, the fire gave experts an exceptionally rare opportunity to investigate parts of the cathedral’s structure that were previously inaccessible, revealing forgotten burials and providing insight into the working methods of medieval craftsmen.

“The site made it possible to collect an enormous and unprecedented quantity of data on the materials used in the construction of the masonry of the cathedral and on the way in which these materials were worked and assembled,” explains Yves Gallet, professor at the University of Paris. history of medieval art at Bordeaux-Montaigne University, who heads the working group studying the masonry of the cathedral. “To do this, we needed to be able to examine the walls, pillars and vaults very closely, which we were able to do from the scaffolding, with unparalleled precision in observation and data recording, and with the possibility of taking samples. from places that were not previously accessible.

Piles of debris sorted for study or reuse

Once the fire was brought under control by firefighters, experts began the complex work of securing the building and sorting through piles of damaged materials, both for study – to guide future restorations – and in the hope that ‘a part can be reused. These specialists were divided into nine working groups – including metal, stone and glass – and archaeologists excavated spaces where scaffolding and cranes would be installed and carried out geophysical studies. As molten lead contaminated the air and materials, researchers had to collect and analyze them with extreme caution. Experts operated remote-controlled robots – one with a bucket, the other with a claw – to pick up materials and move them to safe areas, wore protective clothing and masks and even used on-site decontamination showers .

As the work progressed, archaeologists uncovered the remains of a 1st century building under the Soufflot crypt; excavated more than 1,000 sculpted fragments of the rood screen destroyed in the 18th century; and identified more than 100 lay and clergy burials. Significantly, they also found two lead coffins in the transept, the place of honor for burial. One of these coffins contained the remains of Canon Antoine de La Porte, who died in 1710 and identified by a plaque on the lid of the coffin. The other body was anonymous, but has since been identified as that of Joachim du Bellay, a 16th-century poet and former canon of Notre-Dame.

“We identified a man who died between 30 and 40 years old, autopsied and presenting bone and meningeal lesions caused by tuberculosis,” explains Eric Crubézy, professor of biological anthropology at Toulouse III-Paul Sabatier University, who studied the body. “These findings form a set of arguments pointing towards Joachim du Bellay. Indeed, individuals buried in the cathedral in this age group were rare, and the likelihood of discovering such lesions was even rarer. All these elements reinforce the hypothesis of an identification with Joachim du Bellay, whose biography we have re-examined.

Researchers have also made surface discoveries. The fire revealed previously unknown iron elements in the cathedral’s structure, studied by the metal working group, while the wood working group examined the approximately 10,000 pieces of the burned wooden roof of the building to better understand its assembly and construction, and even to reconstruct French architecture. climate in the Middle Ages. The stone working group, for its part, gained valuable information on the methods used by medieval stonemasons.

“The fire also caused the collapse of certain vaults, thus making it possible to examine them ‘from the inside’,” comments Gallet. “Surprising discoveries were made, such as the very thin thickness of the vaults, the presence of hundreds of masons’ marks and the remains of one of the oculi (circular windows) from the 12th century in the walls of the apse (east end), although It is believed that these oculi were removed in the 13th century, which will make it possible to better reconstruct the appearance of Notre-Dame in its original state in the 12th century.

These discoveries confirm the extensive knowledge of medieval stonemasons and masons, Gallet says, but show that they were also experimenting. In the nave, the stonemasons seem to have hesitated to coordinate, for example, the ribs which support the vaults. Once all this data has been digested and cross-referenced with the results of other working groups, the experts will undoubtedly have to review the detailed chronology of the construction phases of the cathedral in the 12th and 13th centuries, adds Gallet.

“The most surprising thing is to be able to discover so much new information about a cathedral which is undoubtedly the most famous in the world, and to realize that despite its fame, Notre-Dame still retains part of its mystery,” explains Gallet. “What is also surprising is to realize that the construction is full of approximations and irregularities, even though it is considered the embodiment of the perfection of Gothic architecture.”