Between the two wars, the head architect of the Monuments historiques, Petitgrand, attempted to bring the vast restoration project for the east wing to a successful conclusion. He was thinking, in particular, of the Saint-Gabriel chapel. Between1941 and 1950, under the supervision of the architect Sylvain Stym-Popper, (head architect for the Monuments Historiques at that time) and Paul Mesplé, museum curator, a complete restoration project for the gothic church was implemented. This included the restoration of the rose-window on the west facade of the church, the choir vault, the restoration of the side chapels, the reconstitution of the upper windows and almost all the capital friezes of the vault springings. This ambitious project was resumed in 1969 by the architect Yves Boiret and by the museum curator, M. Denis Milhau. The original levels, buildings, spaces and volumes were restored. A garden giving on to the rue des Arts and based on the concept of "la cour anglaise", revealed the foundations of the east chapels that were destroyed between 1805-1828. All 19th Century additions and modifications were removed. Restoration began on the west gallery of the large cloister and the medieval door of the Saint-Laurent chapel, which opens into the Viollet-le-Duc wing, whose shell was conserved. Work carried out between 1975 and 1981 actually increased the surface area of the exhibition halls (creation of mezzanines), and finalised restoration of the convent, whose role would be to house the new collection of gothic art. Only the building for the museum entrance and the door from the Penitents Noirs chapel (removed during the demolition of this chapel in the 60s) were added. This work enabled the museum to bring to the old convent some remarkable organs made in the classical German style by Jürgen Ahrend.