The Château Comtal of Carcassonne was mostly built in the 13th century, most certainly after the Treaty of Paris of 1229. The former palace of the Viscounts of Carcassonne and the Sainte-Marie chapel were then framed by the towers and curtain walls of the castle. The monument is separated from the city by a deep ditch and defended by two barbicans: one to the east, facing the city, and one to the west which descends to the banks of the Aude. Though access to the castle and its ramparts is not permitted, organized and guided tours allow visitors to discover parts of the historical monument.