The remains of the Castle can be visited
Château de Quillan

Quillan Castle is a castle located in Quillan, France.
Location+
The castle is located in the commune of Quillan, in the French department of Aude.
History+
Quillan is mentioned in a judgment by Charlemagne's commissioners in favor of Daniel, Archbishop of Narbonne, on June 3, 782. The first mention of the castle dates back to 1125. During the Albigensian Crusade, Simon de Monfort seized Quillan, which was part of the possessions of the Archbishop of Narbonne. The latter was the suzerain of the Niort family, who were active supporters of Catharism. Archbishop Arnaud Amaury of Narbonne complained to Pope Honorius III about the confiscation of Quillan in September 1216. The Pope ordered its restitution in March 1217. In 1224, Amaury de Montfort ceded all his rights over Occitania to King Louis VIII. The king then claimed jurisdiction over Quillan and its attachment to the royal domain, which the Archbishop of Narbonne disputed. In 1255, the inhabitants of Quillan recognized the castle as belonging to Archbishop Guillaume de la Broue. Philip III the Bold confirmed in 1280 an agreement between his officers and Archbishop Pierre de Montbrun. In 1332, the castle was still held by King Philip VI of Valois. It then fully entered the possessions of the Archbishops of Narbonne. The current building appears to have been erected in a single campaign of homogeneous work, between the end of the 13th and the beginning of the 14th century, based on earlier fortifications. It presents an original design, consisting of a square enclosure reinforced at the corners by watchtowers and on one side by a gatehouse. Buildings must have existed inside. A missing floor of the tower must have housed the defensive elements observed on other comparable fortifications, such as in Carcassonne. Attacked by Protestants in 1573, part of the buildings were burned.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: Hervé Rebours
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 42.8746, 2.1868