The origins of the Abbey of Alet-les-Bains are unknown other than that of a priory in the eighth century. It was likely founded by Bera, viscount of Razes. By the twelfth century, it had a lot of influence and a large number of pilgrims. In 1318, the abbey became a bishopric in order to continue the fight against the cathars; as it stayed until the French revolution.
The diocese had eighty Parishes and spanned from Formigueres to Saint-Paul-de-Fenouillet. A wall, with 4 gates, built in the twelfth century to protect the abbey can still be seen today. The Diocese of Alet was one of several bishoprics created in 1317 in the wake of the suppression of the Cathars. In Alet the bishops were also the abbots of the already existing monastery there and the cathedral of Our Lady was built next to the abbey.
In 1577 it was largely destroyed by the Huguenots during the Wars of Religion and was not subsequently rebuilt. The immense Gothic quire was demolished by order of the last bishop, Charles de la Cropte de Chancerac in 1776. The diocese of Alet was not restored after the French Revolution and by the Concordat of 1801 its parishes were added to the Diocese of Carcassonne.
In the sixteenth century, during the wars of religion, as we said the Huguenots burnt and destroyed the abbey. In the seventeenth century, Nicolas Pavillon, bishop of Alet who stood up against the government of Louis XIV; could have found the means to repair the abbey, but did not feel that given the poverty of the people in his diocese, it would be acceptable. He did however build a bridge that spans Aude, in 1662 and gave an improved system of irrigation.
The thirty-fifth and last bishop of Alet, Charles de la Cropte de Chanterac, who opened the “Grande route” (Big road) Limoux-Quillan, also built a new portion of the bishopric, which he attached to the oldest part of the bishopric, which dates from the twelfth century and is now preserved. By climbing a flight of stairs, one would come to the first floor where one can see the beautiful and large synod hall as well as the library. The bishopric and its three hectactres of gardens span a large portion of the old abbey. By the separation of church and state, the bishopric became the property of the persons who lived in his estates, which were disperced around the region. The buildings were used until the beginning of this century.