Thorn Abbey Church is a Gothic church built mainly in the 14th century. The Benedictian abbey was originally founded in 975 by bishop Ansfried. The oldest parts in the western part date from c. 1150. The abbey was closed in 1797 and after that its church has server as a parish church. It was restored in 1860-1881 by Pierre Cuypers.
There is a famous mummy located in the glass sarcophagus in the church crypt. The rich interior contains Renaissance and Baroque style altars from 1624 and 1769, a font from the 15th century and organs from the 18th century.
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.