Coordinates: 51°51′47″N 2°14′56″W / 51.863°N 2.249°W
Gloucester Castle was a castle in the city of Gloucester in the county of Gloucestershire. The castle was demolished and Gloucester Prison built on the site.
Probably constructed by Roger de Pitres, who was also the first Norman Sheriff of Gloucester. It began as a simple motte and bailey castle during the reign of William the Conqueror when sixteen houses were demolished to make way for it. It was enlarged by William Rufus who demolished eight more houses. It was placed in the custody of the sheriff of the county, Walter of Gloucester.
Before 1112 Walter built a new castle west of Barbican hill on a former garden of Gloucester Abbey, overlooking the River Severn. The hereditary sheriffs of Gloucester held Gloucester castle until 1155 and later it was retained by the Crown.
It was further extended by Henry I and Henry II. More improvements and some repairs were carried out by Henry III, these improvements including a bridge across the River Severn leading to a barbican in the outer wall. Henry III often used it as a residence, and it played an important role in the barons' war when it was besieged twice in 1264-5. Part of the castle had been being used as a gaol by 1185 and it was probably then the official county gaol, as it certainly was by 1228, and Eleanor of Brittany, niece of King John and cousin of Henry III with a better claim to the throne according to primogeniture and thus becoming a state prisoner, had been briefly imprisoned there during the reign of John, from 1222 to 1223, and from 1237 to 1238, and for the second time its prisoners had to be transferred to accommodate her.