Osterstein Castle is the former castle of the town of Zwickau, today it houses the nursing home.
First mentioned in 1292, it was badly damaged in a fire in 1403, and demolished between 1404 and 1407 under William I, Margrave of Meissen. It was rebuilt during the reign of Christian I, Elector of Saxony in 1587-1590 as a magnificent Renaissance castle.
In the 18th century Zwickau Prison was established in the castle, which with interruptions, was used until after the Second World War. There were numerous prominent prisoners, including Karl May, August Bebel, Rosa Luxemburg and Martin Hoop.
During the Second World War, it was used as a concentration camp. On 31 December 1962, after 187 years, the use of the castle as a prison ended, although a public bathhouse continued to operate in an intermediate wing of modern construction, on the Dr.-Friedrich-Ring. The former arsenal and the cell block were used to house the archives of the local coal mining industry, and for storage by various local businesses. Parts of the premises were demolished.
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.