Chester Castle is sited at the southwest extremity of the area bounded by the city walls and overlooking the River Dee. The castle was built in 1070 by Hugh d’Avranches, the second Earl of Chester and hosted visits from many powerful figures in the medieval period, including kings Edward I and Richard II.
The original structure would have been a Saxon motte-and-bailey castle with a wooden tower, which was replaced in the 12th century by a square stone tower, the Flag Tower. The walls of an outer bailey were built in the 13th century, during the reign of Henry III.
Prominent people held as prisoners in the crypt of the Agricola Tower were Richard II and Eleanor Cobham, and Andrew de Moray, hero of the Battle of Stirling Bridge. The Agricola Tower is a Grade I listed building. It is built in sandstone ashlar with a metal roof in three storeys.