The Interior Restoration of Notre-Dame de Paris (1845–1869): A Historical Study for an Architectural and Acoustic Reconstruction

The PHEND (Past Has Ears at Notre-Dame) collaborative research project is being carried out by a team of multidisciplinary researchers interested in the acoustic history of Notre-Dame Cathedral in Paris. The project involved the creation of seven digital models representing the interior of the monument between 1182 and 2018. To support one of the virtual reconstructions, that of 1868, a technical report was drawn up based on the written and iconographic archives of the restorations carried out between 1845 and 1870 by the architects Eugène Viollet-le-Duc (1814–1879) and Jean-Baptiste-Antoine Lassus (1807–1857). The archives come mainly from the “Fonds Viollet-le-Duc”, from the work diary of the “Médiathèque du patrimoine et de la photographie” (MPP), and from the archives of the Notre-Dame chapter. In order to select the most relevant data for the digital reconstruction, the research addresses specific questions regarding the cathedral’s materiality, such as structural modifications, restorations, and the choice of materials and furnishings. To understand how the interior of the cathedral was transformed in the 19th century, a detailed inventory of its condition was compiled at two points in time: at the beginning of the restoration in 1848 and following its completion in 1868. In parallel with this work, to provide a graphic representation of the changes that had occurred in each area, comparative illustrations were produced showing the situation before and after restoration. The modifications were then detailed by area: general restoration (vaults, openings, paving), and redevelopment of the choir and the main body of the building (chapels, transept, nave). This research revealed the building’s profound structural changes and the fact that the renovations spared no space. These included mainly modifications to the high windows, a complete redesign of the decorative layout of the choir and chapels, the restoration of all the vaults and paving at different levels, and a complete restoration of the organ.