The lords of Aarwangen were first mentioned between 1194 and 1212 as a Ministerialis (unfree knights in the service of a feudal overlord) family in service to the Kyburgs. Starting in 1266, Walter of Aarwangen was in the service of the future King of the Romans Rudolph I. Initially they owned land in the Emmental, but in 1276 they sold the land to Trub monastery. Around 1300 they built the tower of Aarwangen Castle along the banks of the Aar river. In 1313, they were firmly established in Aarwangen when Rudolf III of Neuenburg-Nidau granted them the bridge over the Aar river as a fief. After Walter's death in 1320, his son Johann took over the castle and leadership of the family. Johann was a patron of the Cistercian Abbey of St. Urban in Hasle, Lucerne and in 1341 he joined the Abbey. He remained at the Abbey until his death in 1350, which ended the Aarwangen noble line.
After the Aarwangen family died out, the castle went to the Grünenberg family. They sold it in 1432 to the city of Bern. It served as the seat of the Bernese bailiff until 1798. It is now the administrative seat of the surrounding district.
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.