The Lycée Henri IV school is built on the site of the ancient abbey of Sainte-Geneviève erected in the 6th century. Towards the end of the 18^th century, when it is sold as a National Good (Bien National), the site is dedicated to teaching. The construction of the western wing on which we worked dates from 1665. Since then, there have been multiple transformations particularly in terms of partitioning. h2o architects was commissioned to create boarding facilities for young girls of the lycée Henri IV on the three floors of this wing. The site, listed as a Historic Monument, situated in a direct co-visibility with the Pantheon and occupied during the building works, is particularly sensitive. The challenge is to respect the ancient building but to create bedrooms, common rooms and toilet facilities which are comfortable for users. The refurbishment of the work and rest rooms include adapted furniture and on optimal use of natural light. To ensure an easy access to the boarding house, a vertical circulation is created inside the building.