The first house was built in the 11th century. It was a Benedictine Priory which was unified with the abbey of Saint-Victor. To discover it, place yourself in front of the door leading to the cloister (from the main street).
Notice the overhanging stones above the cloister’s entrance. We call them corbels. They give us the location of the bridge allowing the canon priests to get back to their housings.
Follow the imaginary bridge and you will end up facing a small walled up medieval door. Here laid the former priory. While looking closely at the façade, you will notice a pointed arch and other medieval architectural details.