Brochs are ancient settlements - some existed as isolated dwellings whilst others were the heart of small villages. The Broch of Gurness is publicly accessible and managed by Hostoric Scotland. It is one of the most impressive of over 500 brochs known to exist and overlooks the island of Rousay.
Built sometime between 500 and 200BC it consists of high double skinned stone structural walls (some were up to 13m high at other sites) and defensive walls with deep ditches. It features stairs to an upper level. Brochs are characterised by a tapering cylindrical shape, thick double walls and a main central room with a single door for access and no windows.
The site was abandoned at some point and a subsequent house built on part of it around 100BC. It was also reused as a Viking burial ground c.600-800 AD.
Of note it also has a cistern excavated 5m deep in the centre of the floor. The narrow (impractical) steps and the shallow depth of water imply to archaeologists that this was used for ritual rather than practical purposes. The cistern is covered with a grating but the interior can be viewed with torch.
The site is open access with free parking and useful information boards.