For more than a decade, the agency has been carrying out a long-term restoration project on the monument, characterized by its large stained-glass windows and the introduction of innovative principles such as ribbed vaults. Its western façade is an important milestone, both in the history of medieval sculpted portals and in that of monumental restoration in the 19th century. It has been classified as a Historic Monument since 1862.
In 2015, the western façade underwent extensive restoration work commissioned by the Île-de-France Regional Directorate for Cultural Affairs (DRAC). Numerous damaged facing stones and widespread grime were detracting from the architectural appearance of the building and its sculpted decoration. The restoration work restored a uniform appearance to the different levels of the façade and reestablished the polychromy intended in the 19th century by architect François Debret (1777-1850) to discreetly highlight the architecture. The sculptures on the portals, most of which date back to the 12th century, were meticulously cleaned and consolidated using techniques adapted to the specific characteristics of each stone and the presence of ancient polychromy.
The work also focused on finishing touches that are essential to the façade's appearance, such as stained glass windows, woodwork, and the clock, which was restored to its central position.
