 Pope Innocent III initiated a crusade to extinguish Catharism in southern France, with great loss of life.In the aftermath of the crusade, the cathedral's dominant presence and fortress-like exterior made of brick were intended to demonstrate the authority of the Catholic Church, to protect its sanctuary by thick walls, and to convey a sense of poverty in response to Catharism.The instigator of the cathedral's construction was Bernard de Castanet, Catholic Bishop of Albi and Inquisitor of Languedoc.