https://www.scientificamerican.com/article/a-huge-scientific-effort-is-studying-notre-dames-ashes/

The fire that destroyed large sections of the iconic cathedral Notre-Dame de Paris last April was a national tragedy. Now, months on, scientists with the French national research organization CNRS are embarking on a multimillion-euro effort to study the 850-year-old building and its materials with the goal of illuminating how it was constructed. With unprecedented access to the cathedral’s fabric—including timber, metalwork and the building’s foundations—in the wake of the fire, scientists also hope that their work will arm them with information to help the restoration.

The research could “write a new page in the history of Notre-Dame, because there are currently many grey areas”, says Yves Gallet, a historian of Gothic architecture at the University of Bordeaux-Montaigne, who is in charge of a 30-strong research team investigating the masonry.