Classified as a National Monument since 1910, the Domus Municipalis is a rare example of Romanesque civil architecture. The building had the dual function of being a cistern and the headquarters of the municipal meetings. The cistern, underground, has a barrel vault reinforced by two arches, while the upper body, divided by an arcade, forms a wide gallery where the affairs of the municipality were discussed. Under the cornice runs a series of corbels with late Romanesque motifs. Without consensus among experts, the construction of the building is supposed to have taken place between the 12th and 15th centuries.