Built around 1525 as part of the castle’s fortifications, the structure is constructed from randomly coursed rubble with dressed quoins, connected to the main castle by a rubble stone bawn wall featuring gun loops and a crow-stepped crenellated parapet. The original studded wooden gate remains in place on the eastern side, hanging beneath a striking round arch where alternating sandstone and limestone blocks create a distinctive banded pattern.

The gatehouse’s defensive capabilities are evident throughout its design. A segmental arched vault runs east to west through the main gateway, whilst two high vaulted chambers flank the northern side of the entrance passage, accessed through round-arched doorways and lit by narrow slit openings. A musket hole guards the southern approach, and buttresses support the structure to first floor level on both the eastern and southern walls. The northeast tower houses a stone spiral staircase, entered through a square-headed doorway of chamfered limestone, providing access to the upper floors where later residents added more comfortable features during renovations in 1738.

The upper levels reveal a blend of medieval defensive architecture and later domestic improvements. The first floor features a fireplace with a plain segmental arch on the north wall and an elegant double-light window with mullion, transom and cusped ogee heads on the east side, though a crack now mars the base of its arch. A small mural chamber adjoins this floor, illuminated by simple rectangular windows. The second floor, accessed through a pointed arch doorway of chamfered limestone, contains a later fireplace inserted into the northwest corner and an ogee-headed window on the western wall. Along the western parapet, a pointed arched window has been cleverly incorporated into the battlements, allowing defenders to maintain watch whilst remaining protected.