Ruins of the Old Bishop's Palace

The ruins of the Old Bishop's Palace are the remains of a planned single bailey castle, designed with the main defense located in the gatehouse and walls above the river escarpment. The gatehouse features twin towers, originally having two floors above a basement. It includes an archway with three vaulted bays that retain the original moulding, a portcullis slot, and a rebate for the surviving ancient oak doors, which are heavily reinforced with iron strapping and studding. The north-east tower is depicted in John Speed's view from 1610, along with other towers along the south wall, of which traces still exist. The curtain wall is most complete along the west front, while only remnants of the original upper rooms can be found.

Currently, there is no evidence of structures within the walls, except for indications of a first-floor Great Hall in the corner above the escarpment. John Speed's illustration from 1610 shows the walls and towers intact, but does not depict any internal buildings. Single bailey castles like this one, which had limited accommodation within the walls and towers, typically featured timber buildings within the bailey, similar to Caldicot Castle in Monmouthshire. The interiors of the gatehouse were not accessible during the resurvey, but it is noted that the north tower has an unlit semi-basement, while the south tower contains a well-appointed ground floor room with a hooded fireplace and arrow loops facing three directions. A square turret at the back includes a spacious newel stair, which likely provided access to the room above, spanning the full width of the gatehouse.