Schwanau island in Lake Lauerz is occupied by a ruined castle, a chapel and a restaurant. Traces of occupation on the island date back to around 1200 BC. There is little documentary evidence relating to the castle, but it is believed to have been built at the end of the 12th century and to have been ruined, probably as a result of a fire, as early as the middle of the 13th century.
The island in known to have been occupied by hermits at various times, including the 17th and 18th centuries. In 1684 a chapel was built on the island, but this was destroyed by the tsunami that followed the 1806 Goldau landslide. In 1808 the council of the church in Schwyz sold the island to General Ludwig Auf der Maur on the provision that he rebuild the chapel. The island remained in the possession of the general's descendants until 1967, when it was purchased by the canton of Schwyz. In 2009 it was completely renovated.
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.