The construction of the Klingnau castle, originally the seat of the Klingen family, was started in 1240. Until 1269 a manor house stood on the grounds. After 1331 the outer walls were added. In the second half of the 14th century the Bishop of Constance was often a resident in the castle. He ordered further improvements and expansions.
In the late 16th century, the castle, which was the seat of the bailiff from Constance, in such bad condition that the Swiss Confederation demanded a renovation from the bishop. In 1804 the castle went to the newly formed Canton of Aargau, who auctioned it off in 1817. As a result it has been used by various industries, until the 20th century when it was taken over by a foundation.
References: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.