The ruins of the castle of Monségur, last fortress of the Catharist resistance, date back to a reconstruction following the crusade. What remains are massive quadrangular walls, with two doors and a courtyard having rocky outcrops. On the highest point there is a building formerly covered with a tunnel vault, with little windows: it was probably the main tower or another lodging. For guided tours (groups of 20 people and more) tel. 33 (0)5 61 01 06 94.