Frösunda Church was built in the 15th century to the site of older wooden church. The baptismal font of sandstone dates from the late 12th century. The altarpiece dates probably from the 15th century and is carved in Germany. The rococo style pulpit was carved by Magnus Granlund in 1759.
The external bell tower was mentioned first time in 1631. There is also a 11th century runestone outside the wall.
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.