Although Siersberg Castle was first mentioned in 1178, it was probably already built in the 11th century. It was built atop an almost 300-meter-high mountain overlooking the valleys of the rivers Saar and Nied.
During the Thirty Years' War, in 1634, the castle was taken by French troops. In the next decades it was taken and retaken several times by both parties, which of course caused damage to the castle. In 1670 the French again occupied Lorraine. When they retreated again in 1677 they partly blew up the, by then already dilapidated, castle. After that, Sierberg increasingly lost its military importance and its decay progressed.
References:Sigmaringen Castle was first mentioned in the year 1077 in the chronicles of Petershausen monastery. The oldest parts of the castle are concealed beneath the alterations made during the 17th and the 19th centuries. The secret of the earliest settlement built on this defendable rock will never be fully revealed: large-scale excavation work would be necessary, which the extensive land development renders impossible. Judging from the many Roman remains unearthed in the area around Sigmaringen, the 12th century keep known as the 'Roman Tower' could be traced back to a Roman predecessor.
The castle remains that have been preserved (gate, great hall and keep) date back to the Staufer period around 1200. The castle remains were integrated into subsequent buildings. The foundations of the castle buildings are to a large extent identical to the surrounding castle wall.
These remains give us a good idea of how the castle might have looked during the 12th century.