The monument consists of a bastle, two storeys and a garret in height, standing on the S slope of Mervin's Law. To the south of the bastle are the remains of associated buildings situated in a depression scooped out of the hillside. The remains represent a small semi-fortified estate centre dating from the mid-to-late 16th century. The monument was first scheduled in 1948. On this occasion an inadequate area was included to protect all of the archaeological remains: the present rescheduling rectifies this.
The bastle is intact apart from the loss of its roof. Its masonry is roughly coursed rubble with distinctive pinnings, set in clay, and the numerous quarry-pits that are to be seen close to the building suggest that the material was obtained locally.
It measures 7.77m from NW to SE by 6.5m transversely over walls about 1.2m in thickness, the wall-heads being about 5.5m high. As with many bastles, the main axis of the building runs parallel with the slope, with the ground floor door situated in the downslope gable. Each storey contains a single unvaulted apartment. The ground floor entrance is in the SE; the first floor must have been reached via an external ladder or forestair abutting the SW wall, in which there is an entrance. The garret, which must have been reached by an inside ladder, has one small window facing SE. None of the floors has a fireplace, but at first floor level, a line of joist pockets in the NE wall, slightly above floor level, may represent the remnants of a hearth.
The hillside below the SE gable has been scooped out to varying depths. This excavation, which is roughly D-shaped, seems to have been bounded on its lower and straight side by a wall, extends over an area measuring some 45m from NW to SE by 41m transversely. Against this wall, and roughly in line with the bastle, there are the foundations of an oblong building which measure about 7.3m from NW to SE by 4m transversely within walls about 0.9m thick and gables about 1.2m thick. Some 9m to the NE there are the remains of a second building, and beyond this a third building occupies the E corner of the enclosure.
The area to be scheduled includes the bastle, the associated buildings and an area in which associated remains can be expected. The area is quadrangular in shape, and has maximum dimensions of 100m NE-SW and 90m transversely as marked in red on the attached map.