1 Type of early Iron Age structure found in Shetland, rectangular in ground plan, three storeys high, heavily built, with a central passage at ground floor level, domestic accommodation to either side of the passage and on the first floor, and with a wall‐walk and vantage point on the top floor. At the rear of the stone building was a small timber extension with a range of further accommodation.
2 A small strongly built defensive structure used specifically to house guns and to protect the gunners and ammunition from attack. Usually built of stone, blockhouses were typically sited to command a river, harbour entrance, or anchorage, or as an outlying work to provide enfilading fire or protection to other defensive works. Accommodation within the blockhouse is confined to the short‐term needs of the gunners or garrison. The basic design involves a tower dominating a bastion or gun platform, usually with a ditch or moat on its most vulnerable side. Built mainly between the late 13th and mid 16th centuries. Also known as gun towers.