Gnandstein castle was built in the Romanesque style in the 13th century, probably only with a rectangular groundplan and a residential tower. Parts of the present building still date from this early period. The external walls were extended several times.
During the Thirty Years' War the castle was attacked by Swedish troops and partly destroyed. Shortly before the end of the war the south wing burned down after being struck by lightning.
The well house is more than 33 meters high, giving the visitor a broader view of the region. It was used as a watch tower. Guided tours are available.
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.