Pustý hrad is a castle whose ruins are located on a forested hill in the southern part of Zvolen in central Slovakia. With an area of 76,000 m² it is arguably one of the largest medieval castles in Europe. The original name was Zvolen Castle or Old Zvolen; Pustý hrad (meaning "deserted castle") is a much later name used to distinguish the ruin from the present-day Zvolen Castle.