The Broch de Mousa is a brooch located on the Isle of Mousa in Shetland, Scotland. It is the best-preserved brooch that has survived, and it is also the tallest still standing, at 13 meters high. It is also one of the best-preserved protohistoric buildings in Europe. It is estimated that it was built around the year 100 BC. Historic Scotland currently manages the site.
Its excellent state of conservation is indeed explained by its particularly massive aspect and its isolated character, the island of Mousa being currently uninhabited. It can also be defined by its walls, among the widest there are, and by its smaller diameter than the other brooches. Moreover, it has only one entrance.