Bonshaw is a 16th Century rectangular tower house of 3 storeys and a garret within with the corbelled-out parapet. The walls are pierced with gunloops, but the pitch of the roof has been altered.
The entrance leads to a mural passageway into the vaulted basement and to the turnpike stair. There is a cramped pit-prison within the thickness of one wall. The hall, on the first floor, has a wide fireplace.
Bonshaw is the seat of the Irvine or Irving family. William de Irwin or Irvine was armour bearer to Robert the Bruce, and granted Drum in Aberdeenshire as reward for long service. Bonshaw was sacked in 1544 by the English, but twice successfully withstood sieges by Lord Maxwell in 1585. The Georgian house adjacent to the tower is also in ownership of the Irvings.