Špilberk Castle (German: Spielberg) is an old castle on the hilltop in Brno, Southern Moravia. It began to be built as early as the first half of the 13th century by the Přemyslid kings and complete by King Ottokar II of Bohemia. From a major royal castle established around the mid-13th century, and the seat of the Moravian margraves in the mid-14th century, it was gradually turned into a huge baroque fortress considered the heaviest prison in the Austro-Hungarian empire, and then into barracks.