Austrått Fort is a disused coastal artillery site constructed in 1942 by the German Wehrmacht to protect the Trondheimsfjord during the German occupation of Norway during World War II. The fort's centrepiece is a triple 28 cm SK C/34 naval gun turret from the German battleship Gneisenau, which was damaged in Kiel. The three gun turret weighs 800 tonnes and was capable of firing 38 kilometres. The last firing took place in 1953 and the fort was decommissioned in 1968. It opened as a museum in 1991.
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.