The Palais des Évêques was once the home of the powerful bishops of Couserans. The oldest parts of the complex date from the 13th century, while much of the palace was enlarged during the 17th century. Its thick stone walls, round towers and elevated position gave it the appearance of both a residence and a fortress.
After the bishopric was abolished in 1801, the building served several purposes, including as a town hall, prison and psychiatric hospital. Today, it houses the Departmental Museum of Ariège. The adjoining Notre-Dame-de-la-Sède Cathedral is especially famous for its colourful Renaissance wall and ceiling paintings.