Helga Trefaldighet (Holy Trinity) Church was inaugurated in 1302. It replaced the previous church of local Ullerås parish. The church is made of grey stone and brick and it was originally a three-nave basilica. The western tower was added in the 15th century. The church was damaged badly by fire in 1702.
The interior is particularly notable. It is decorated with paintings by the famous medieval artist Albertus Pictor, which were created in the second half of the 15th century. Of particular interest is the depiction of The Visitation, regarded as one of the finest surviving medieval paintings in Sweden.
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.