The Sponeck castle was built in the late 13th century to the site of late Roman fort (built by Emperor Valentinian I around 365 AD). The castle was destroyed in the Thirty Years War. After several changes of ownership the painter Hans Adolf Buhler acquired it in 1917, rebuilt and set up a studio in the former residential tower. After the painter's death in 1951 the castle was owned by the family. Today the stone wall and two corner towers are preserved of an original Roman fort.
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.