Chateau des Clées is located above the village. Built probably in the 11th century, it guarded the traffic through the Jougne Pass and collected tolls on the pass road. Les Clées is first mentioned in 1134 when Pope Innocent II tried in vain to prohibit the reconstruction of the castle.
The chapel of Les Clées was built before the 14th century and rebuilt in 1738-1740.
In 1444 the Duke Louis I of Savoy commissioned the renovations of the walls. During the Burgundian War, on 22 October 1475, Swiss Confederation troops seized and destroyed the city and castle and killed the castle garrison. Under Bernese rule there were three courts in the Les Clées district, one of which was held in the city. Nevertheless, the city gradually lost importance.
Today Les Clées Castle with the surrounding ruins and village is listed as a Swiss heritage site of national significance.
The Château de Foix dominates the town of Foix. An important tourist site, it is known as a centre of the Cathars. Built on an older 7th-century fortification, the castle is known from 987. In 1002, it was mentioned in the will of Roger I, Count of Carcassonne, who bequeathed the fortress to his youngest child, Bernard. In effect, the family ruling over the region were installed here which allowed them to control access to the upper Ariège valley and to keep surveillance from this strategic point over the lower land, protected behind impregnable walls.
In 1034, the castle became capital of the County of Foix and played a decisive role in medieval military history. During the two following centuries, the castle was home to Counts with shining personalities who became the soul of the Occitan resistance during the crusade against the Albigensians.