There are about 30 Cathar Castle sites, in Aude, from the 13th Century, that can be still explored today...
Castle Tours
"These are historical tours centred on the Cathars of the Languedoc, on location in the Pays Cathare "Cathar Country" in Southern France. The Cathar movement and the Albigensian Crusade against the Cathars were two of the most important events in European history - with many, often surprising, world-wide resonances even today, eight centuries later. The tours are led by James McDonald who is English speaking." http://www.catharcountry.info/
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Puilaurens first appears in the historical record as a possession of the Abbey of Saint-Michel-de-Cuixà in 985AD. It is the most southern castle in France, it was a key fortification on the border between France and Aragon, and changed hands more than once. At an altitude of over 700 metres, it looks down on the village of Lapradelle.
The Château de Puivert (Languedocien: Castèl de Puègverd) is a Cathar castle situated in the commune of Puivert. The castle has been classified as a monument historique by the French Ministry of Culture since 1902. This building, on top of a hill overhanging the village and its lake, reaches an elevation of 605 m. The site is in the Quercob region, 60 km (37 mi) south of Carcassonne and 45 km (28 mi) east of Foix.
Carcassonne competes with Mont St Michel for the title of the most visited monument in France. The citadel was restored at the end of the 19th century and in 1997 it was added to UNESCO’s list of World Heritage Sites.