The Vikings had a stronghold at Aggersborg surrounded by an enormous rampart. Towering to the north of the rampart there is a church of Aggersborg, probably erected during the 12th century. An interesting illuminated inscription of runes can be seen on the walls of the nave and the northern chancel wall. The altarpiece dates back to 1598, but it wasn't placed in Aggersborg until 1934. The previous altarpiece can be seen on the northern wall of the nave. It pictures the founding of The Lord's Supper. There used to be family burial places behind the beautiful lattice.
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.