Oxford Castle Quarter

Oxford Castle is a large, partly ruined medieval castle on the western side of central Oxford in Oxfordshire, England. Most of the original moated, wooden motte and bailey castle was replaced in stone in the late 12th or early 13th century and the castle played an important role in the conflict of the Anarchy. In the 14th century the military value of the castle diminished and the site became used primarily for county administration and as a prison. The surviving rectangular St George's Tower is now believed to pre-date the remainder of the castle and be a watch tower associated with the original Saxon west gate of the city.

Most of the castle was destroyed in the English Civil War and by the 18th century the remaining buildings had become Oxford's local prison. A new prison complex was built on the site from 1785 onwards and expanded in 1876; this became HM Prison Oxford.