The castle of the counts of Toulouse dominates Vaison-la-Romaine from the top of a sheer rock. It was built in 1195 by Count Raymond VI, threatened with excommunion, to replace a tower destroyed by the Bishop of Vaison, Bérenger de Reilhane. A powerful fortress of Comtat Venaissin, the fortified castle comprised defenses and a keep that no longer exist. It recalls the struggles that opposed the counts of Toulouse and the bishops of Vaison, the usurpers of their rights, until Alphonse de Poitiers, the brother of Saint Louis and son-in-law of Raymond VII of Toulouse, imposed on the bishops the restitution of these rights on December 30, 1351.