Watch-tower to west of St Donats Castle

The watch-tower located to the west of St Donats Castle is a roofless square structure made of Lias limestone, featuring steps leading to a first-floor entry at the north-west end. Attached to this structure is a castellated tower that stands 15 meters high and includes a corbel table at the south-east end. The building has chamfered 4-centred doorways, with one doorway at ground level and another above a flight of steps, both of which date from the late 19th century. The north-east elevation includes a 2-light mullioned window above and two single-light windows below. The south-west wall and the tower are heavily overgrown with ivy, making it difficult to confirm some details, but the Royal Commission on the Ancient and Historical Monuments of Wales (RCAHMW) notes that there is a single-light window on each floor of the tower and a small gun-loop in the parapet at the top. The tower features corbelled tops at two different levels, resulting in two distinct levels of roof terrace, with parapet walls that have concrete coping and a mounting for a flag-pole.

Inside the two-storey portion, the structure is essentially a shell, but the stone corbels that support the first floor are visible, along with the two doorways with 4-centred heads leading into the tower. There is also a window on the first floor with a segmental head. The lower room of the tower is featureless, while the upper tower, which contains a concrete spiral staircase, is not accessible.