In 1175 the Freiherr von Weissenburg was first mentioned as a land holder and vassal of Duke Berthold IV of Zähringen. Whether they had a castle at this time is not recorded. When he assumed the title in 1259, Rudolf III of Weissenburg expanded and repaired Weissenburg Castle to its full size. Beginning in the 13th century, the Weissenburgs began to expand their Herrschaft. Around 1250 they added Wimmis to their territory, followed by Weissenau Castle in Unterseen and the villages of Rothenfluh and Balm a few years later. However, Rudolf III sought closer relations with the Habsburgs which made an enemy of the nearby town of Bern. In 1288 he lost a battle at Wimmis against Bern and the village was plundered. Ten years later he quarreled with the Habsburgs and the Counts of Neu-Kyburg and lost control over the Rothenfluh and Weissenau Castles. Then, in 1303, he fought Bern again, this time protecting Wimmis.
Rudolf's son, Johann the Elder, was able to continue expanding the family holdings, adding part of the Hasli valley, Oberhofen Castle and Unspunnen Castle. However, in 1334 he suffered a decisive defeat against Bern and was forced to acknowledge Bern as overlord over the castle and Herrschaft. When his son Johann the Younger died in 1368, the Weissenburg line died out and their estates were inherited by the Lords of Brandis. In the mid-15th century the Lords of Brandis sold all their land holdings in the Bernese Oberland including Weissenburg Castle to Bern. Under Bernese rule, Wimmis Castle became the administrative center of the Niedersimmental and Weissenburg was abandoned. Over the following centuries the castle walls were demolished to provide construction material for houses in the village.
The castle is located on a steep hill west of Weissenburg village near the confluence of the Bunsch stream and the Simme river. The castle is protected on three sides by the steep hill, while the gentler west side is guarded by a still visible ditch. Above the ditch portions of a round tower are still visible. The massive south wall and gate are still standing. East of the castle, the foundations of several small houses of the medieval town can be seen.
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.