The ruined castle Burg Drachenfels, on the summit of the Dhill, was built between 1138 and 1167 by Archbishop Arnold I of Cologne and bears the same name. It was originally intended for the protection of the Cologne region from any assault from the south. Originally it consisted of a bergfried with court, chapel and living quarters for servants. The castle was slighted in 1634, during the Thirty Years' War, by the Protestant Swedes and never rebuilt. As a strategic asset it had outlived its usefulness. Erosion due to the continued quarrying undermined much of the remains and only a small part is left today.
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.