The name may be derived from the Roman personal name, Cossinius, or from the German Kissen (Alemannic Chüssi) which means "cushion", after the shape of the mountain on which it stands.

The hill castle is one of the most important historic buildings on the High Rhine and a landmark of the county of Waldshut.

The castle, which was later developed into a fortress, was destroyed by a fire started by its garrison on 8 March 1634 when the Swedish Army approached it during the Thirty Years' War and by a landslide on 25  December 1664.

In the 19th century work began on uncovering the ruins which have since become a popular destination in the region.

In addition, there are views of the Southern Black Forest and the Aargau in Switzerland.