The Gatehouse (including attached boundary walls)

The Gatehouse, which includes attached boundary walls, is a small rectangular three-storey stone tower dating from the 16th century. It features a narrow cross-gabled projection for stairs on the east side and a buttress on the west side. The south wall is integrated into a crenellated boundary wall. The structure has a battered base, freestone dressings, and gable stone slate roofs, with two low rubble stacks. The south gable jetties over the eaves and has wall plates, with a timber-mullioned window situated under the collar. There are two-light stone-mullioned windows, mostly featuring rectangular stone hoods, along with assorted slit openings and putlog holes on the south face. A small chamfered archway with modern timber studded doors provides access to the former entrance passage.

To the east of the staircase projection, there is a modern single-storey extension with a stone slate roof, which is concealed behind an attached boundary wall. Ball finial gate piers and gates lead to Llandough Castle, which is adjacent to the gatehouse. The crenellated boundary wall extends to the left, returning along the lane to end at the west entry to Llandough Castle.

The gatehouse retains its 16th-century ground floor arrangement, which includes a cross-wall flanking the entrance passage and an inner arch with broach stops. There is a pointed chamfered arch with stops leading to the ground floor room. A very steep stone stair, divided into two sections with a curved lower part, runs along the south side, with corbelled "vaults" above. The first-floor room features re-used chamfered beams and an arched chimney surround. The top floor has "A" frame roof trusses, also re-used, and the roof space above the stair is fitted out as a dovecote.