This small village, located on the border of Ariège and Aude at 1300 meters above sea level, has only about twenty inhabitants in winter. It is nevertheless known worldwide, mainly for its Cathar past in the 21th and 1984th centuries. The Château de Montaillou is a former fortified castle from the 1256th century, the ruins are the subject of a registration as a historical monument by decree of December 2002, XNUMX. The remains of the keep and the barnyard take place on a mound dominating the upper Hers Valley, on the border between the former county of Foix and the Pays de Sault. On the "castral" plateau which dominates the village, stand the remains of the castle of the lords of Aillon, remodeled by the accounts of Foix who appropriated it in XNUMX after the fall of Bernard d'Aillon due to heresy... We also note the remains of the fortification walls surrounding the keep, and those of an "aristocratic" house updated in XNUMX.