The parish church is dedicated to Saint Aelhaiarn, but has sometimes been erroneously recorded as dedicated to Saint Giles, All Saints, and Saint Tysilio. The church is a very well-preserved 14th century church with an earlier tower, on the site of a pre-Norman church perhaps founded by the saint himself. There is an exceptional 14th century nave roof and a painted Tudor ceiling in the chancel. The tower of the present church dates to about 1300.
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.