Dragsmark Abbey was a Premonstratensian canonry, also known as Marieskog in Norwegian. It was founded before 1260, with the support of King Håkon Håkonsson, and was dedicated to the Blessed Virgin Mary. The abbey was very wealthy in its heyday and ran a prestigious school, but declined during the 15th century, and as early as 1519 was in the control of a lay administrator, the first monastery in Norway to be secularised. With the Reformation the Crown granted it to a tenant in 1532, with a condition that the remaining canons had to be maintained. The buildings fell into disrepair, and in 1610 were used as a quarry for stone for the construction of Båhus Fortress.
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.