In the 2nd century AD, the city-sanctuary of Gisacum extended near Saint-Aubin, which was gradually abandoned until disappearing in 5th century. In the 1801 archaeological excavations uncovered this important Gallo-Roman site; but in reality at the time the town covered an area of 250 ha. The interpretation centre has a permanent exhibition tracing the history of Gisacum, and the archaeological garden offers an original development of the thermal baths, which helps to visualise the disappeared monuments, in a pleasant landscape setting.
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.