In a statement, those responsible for the reconstruction and restoration of the cathedral said that the fire of 15 April, 2019 damaged "important" elements of the building, and it is necessary to find a large number of stones that are similar to those of the monument. The research program now published translates into the identification, characterization and selection of stones "aesthetically and physically compatible" with damaged ones and will also serve to create a methodological reference guide for the Cathedral of Notre-Dame and other monuments of the Paris region. The research, which began in July, consists of the geological study of quarries and laboratory tests with several samples, being carried out by geologists, laboratory technicians and other specialists and sediments and geomatics.

The original stones of the cathedral were extracted from the basement of the city, from a vast area of limestone rocks that formed more than 41 million years ago and where there are still about a dozen quarries. During this research, researchers will study the characteristics of these stones in order to find the most suitable for the restoration of the cathedral. Today, French Government spokesman Gabriel Attal indicated that President Emmanuel Macron maintains the goal of completing the works in 2024. The cathedral was under restoration work on its exterior when, in April 2019, a violent fire broke out that took about 15 hours to extinguish. The accidental origin of the fire, a short circuit, remains privileged, although the cause of the fire is unclear, and the calcined residues should be analyzed in detail to detect the slightest indication. Notre-Dame's works have faced several setbacks, from the need to take action against lead contamination to the crisis of the new coronavirus, under bad weather in late 2019, but were resumed in late April.