Torre di Federico is an octagonal ancient tower that was allegedly a summer residence of Frederick II of Hohenstaufen. The two floors possess beautiful vaults. The aspect of the building is austere. It was part of a bigger complex, named Old castle and destroyed by Arabs. Remnants include some pieces of the old, imposing walls on the top of the green hill where the Tower rises.
The tower is an imposing 26 metres high, has a diameter of 17 metres and its walls are 3.5 metres thick.
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.