Mousa Broch, Shetland
Magnificent Iron Age broch on an island off Shetland
Towards the end of the Iron Age in around 500BC defensive forts called brochs became popular.
These circular towers were cleverly constructed using two layers of dry walls and became considered defensive necessity throughout much of northern Scotland.
Of all those that remain, this one at Mousa is the best preserved, partly because you can only reach it by boat: see mousa.co.uk for details of the daily sailing from Sandwick (ZE2 9HP).