Unlike the neighbouring Neurathen Castle very little is known about the history of Altrathen Castle. It was probably built at the same time in the 11th century. The castle was first mentioned in the records in 1289. In 1469 Altrathen and Neurathen castles were slighted.
In 1888 the industrialist, Eduard Seifert, bought the ruins of the castle and rebuilt it in 1893 in a Neogothic style. Of the medieval castle only the cellars and parts of the spiral staircase of the keep have survived.
Aftern 1945 the building acted as a holiday home and later for the East German state bank. In 1995 the site was sold by the Treuhandanstalt to a private owner. Since then the building has been used as a small hotel and restaurant.
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.