The Broch of Mousa is the finest preserved example of a broch or round tower in Shetland, Scotland. It is the tallest still standing in the world and amongst the best-preserved prehistoric buildings in Europe. It is thought to have been constructed around 100 BC and is one of 570 brochs built throughout Scotland.
A broch is a round tower which had an inner and outer drystone wall which was about 5m thick in total. They were clearly both defensive and prestigious buildings.