Osterstein Castle (German: Schloss Osterstein, translated as "The Easter stone castle") is the former castle of the town of Zwickau, Germany, in Saxony (Bundesland Sachsen). Now it houses the nursing home. First mentioned in 1292 as "Castrum Czwickaw", it was badly damaged in a fire of 1403, and demolished between 1404 to 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 (Zuchthaus Zwickau) was established in the castle, which with interruptions was used until the period after the Second World War. There were numerous prominent prisoners, including Karl May, August Bebel, Rosa Luxemburg and Martin Hoop.