All Saints (Alla Helgona) Church was built in the late 1200s, but during the Duke Karl's time (1590-1618) it went through a radical transformation. At the restoration in 1909 the church received its small ridge turrets, which is a replica of the tower on Erik Dahlberg´s engravings of Nyköping. In 1665 the church was ravaged by fire. At the recent restoration in 1959-1960 were the pillars restored in to original condition, limestone from the island of Öland.
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.