broch

A kind of dry-stone-built circular tower up to 30m in diameter and 15m high found widely across the Western Isles and adjacent areas of the Scottish mainland. The walls were hollow, doubled-skinned, up to 3m wide, with chambers inside. In some cases the central court was roofed over, in others there were lean-to structures against the wall faces of the tower. They date to the late 1st millennium bc and early 1st millennium ad and appear to have been the fortified and imposing residences of local lords and chiefs. Some brocks are surrounded by clusters of small houses and yards rather in the form of a small dependent village. The best-preserved broch is the Broch of Mousa on Shetland.