Hohentwiel fortress, whose ruins lie on top of extinct volcano Hohentwiel, was constructed in 914 using stone taken from the mountain itself by Burchard III, Duke of Swabia. Originally, the Monastery of St. Georg was contained within the fortress, but in 1005 it was moved to Stein am Rhein (now in Switzerland), and the Swabian dukes lost control of Hohentwiel. In the later Middle Ages the noble families von Singen-Twiel (12th–13th centuries), von Klingen (to 1300) and von Klingenberg (to 1521) resided here. In 1521, it was passed on to Duke Ulrich von Württemberg, who developed Hohentwiel into one of the strongest fortresses of his duchy. During this time, it began to be used as a prison and in 1526, Hans Müller von Bulgenbach, a peasant commander, was imprisoned there prior to his execution.
The fortress resisted five Imperial sieges in the Thirty Years' War, under the command of Konrad Widerholt between 1634 and 1648. The effect was that Württemberg remainded protestant, while most of the surrounding areas returned to catholicism in the Counterreformation. The castle served as a Württemberg prison in the 18th century and was destroyed in 1800 after being peacefully handed over by the French.
Today the former fortress Hohentwiel is one of the biggest castle ruins of Germany. Hohentwiel’s imposing ramparts and casemates, its fallen towers and defiant ruins, still evoke the military might of this once-invincible fortress. The surrounding volcanic crags are a now a nature reserve, offering a unique habitat to many rare species of flora and fauna. Today, more than 80,000 visitors a year come to admire this special place. The modern city of Singen nestles at the foot of the mountain.
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.