Standing 13m high, Mousa is Scotland's most impressive and best surviving Iron Age tower or broch. A broch is a round tower which had an inner and outer drystone wall which were about 5m thick in total. They were clearly both defensive and prestigious buildings. We now know that brochs were built in Shetland around 400-200BC.
enlarge One reason that Mousa survives so well might be that the diameter is slightly smaller in than others and that its walls are slightly thicker. The walls at Mousa are solid at ground floor level, with three corbelled (beehive shaped) chambers or "cells" within them. The walls are hollow at higher levels, the gap between the two walls narrowing towards the top. The walls are tied together at intervals with stones, which creates a series of internal galleries. There is an internal staircase from first floor level to the top of the tower. From the top there is a commanding view which would made it impossible to approach the island without being seen. The broch of Burraland, on the Mainland opposite would have helped to guard Mousa Sound.
Inside the broch there would have been two wooden floors, evidenced by scarcement ledges (narrow lines of protruding stone) protruding from the inner wall face. Mousa escaped the fate of most brochs which was to be partially dismantled for stone when the inside was remodeled towards the end of the Iron Age. This might be because Mousa flagstone is some of the best building stone in Shetland.
The Orkneyinga Saga tells how in 1153AD, Erland the Young abducted Margaret, widowed mother of an Orkney Earl, and took refuge in Mousa. Earl Harold followed and besieged the broch but found it "an unhandy place to attack".
Find out more about the archaeology of Mousa at: