Located on the west bank of the Kirtle Water, a half-mile southeast of Kirtlebridge and 4 miles (6.5 km) northeast of Annan, Bonshaw is an entirely complete three-storey rectangular tower-house dating from c.1565. There is a crow-stepped gabled garret, inside a parapet, although its flagstone roof was removed in the early 19th century and replaced by slate at a lower pitch. The parapet is drained by cannon-spouts and there are single machiolation openings above each elevation. The entrance is vaulted, with the motto Soli Deo Honor et Gloria above, leading to a vaulted basement. A turnpike stair rises from there to the other floors and there is a cramped window-less dungeon.
Bonshaw is owned by the Irving family and was held, in direct line of descent, for almost 1000 years until Sir Robert Beaufin Irving, a Captain of the liner Queen Mary, died in 1954 without issue. A preservation trust was established in 1975. The tower is linked to an early 19th-century three-bay mansion, which lies adjacent, and both were owned by Dr J. Bruce Irving, Chairman of the Scottish Association of Family History Societies, until his death in 2005.