Marlborough Castle, locally known and recorded in historical documents as The Mount, was an 11th-century royal castle located in the civil parish of Marlborough, a market town in the English county of Wiltshire, on the Old Bath Road, the old main road from London to Bath (grid reference SU18376866). The barrow on which the fortification was built, perhaps the "barrow of Maerla" seems to be a prehistoric earthwork which formed the motte of the Norman Marlborough Castle.