Built in the 12C, the Trencavel Palace was turned into a citadel after 1226. Since the reign of St Louis, an immense ditch and a semi-circular barbican have made it a fortress within the olf walled town. It houses a lapidary museum (note the Calvary of Villanière) and also has two inner courtyards of remarkable architectural interest, boasting numerous towers (west ramparts). On the second floor you can see a film and exhibition explaining the restoration work at Viollet-le-Duc.