Archaeological investigations indicate the site of Oxford Castle, latterly Oxford Prison, has been occupied since the time of the Norman Conquest. The original wooden constructions were replaced with stone structures that eventually formed the western defences of the city of Oxonforde. Having played its part in the 1642-1646 Civil War, the castle fell into disrepair.
Picture engravings, dating back to 1769, indicate the presence of the City Gaol on the site. From that date onwards the prison facilities were enlarged upon, until the latter half of the 19th century when they reached their present stage of development. The prison finally closed in 1996.