Short version - Abli and church area date back to the 10th and 11th centuries. The people of Albi went out on the crusades in the 13th century against Cathars. What are Cathars? I never heard of them before. Simply people who rejected the Roman Catholic Church but still considered themselves Christian. Holy war commence, a lot of people died. Roman Catholic Church won and decided that this was a good way to get rid of a problem. What remains is a now UNESCO World Heritige site to wander around.