Köngen is in the area of the Roman settlement Grinario that was built around 100 AD around a Roman castra. Grinario was the endpoint of the Roman road 'Neckar-Alb-Aare' which originated in Windisch (Switzerland). In 260 the place was destroyed by the Alemanni and the Romans were expelled.
Johann Eberhard Roser discovered some traces in 1782 and started excavations here one year later. At present it is the site of an archaeological park and museum. The earliest reconstructions were those of a Roman corner tower, the originals of which were discovered in 1855. The tower was ready in 1911 and the 'Köngener Römerkastell' with its great viewpoint and small indoor museum soon became a popular excursion.
In World War II and the period short after, the tower was damaged and it was not open to public until 1949. In the 1970s, the tower was fully renovated and a small museum was built next to it.
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.