The fire of April 15, 2019 at the cathedral of Notre-Dame de Paris offered archaeologists and art historians a unique opportunity to work closely with an emblematic building, a World Heritage Site. The recovery of most of the voussoirs from the collapsed transverse arch of the nave has made it possible to study the operating chain of an essential element of the cathedral, from the choice of material to its implementation, including the techniques used by the stonemason or the knowledge of the joiner. This technical analysis has made it possible to establish comparisons with the other elevations of the cathedral, and also with other Early and High Gothic buildings, allowing us to offer a new proposal for the development of knowledge and the overall chronology of construction.