Orkney, also known as the Orkney Islands, is an archipelago in the Northern Isles of Scotland, situated off the north coast of Great Britain. Orkney is 16 kilometres north of the coast of Caithness and comprises approximately 70 islands, of which 20 are inhabited. The largest island Mainland is often referred to as "the Mainland". It has an area of, making it the sixth-largest Scottish island and the tenth-largest island in the British Isles. The largest settlement and administrative centre is Kirkwall.A form of the name dates to the pre-Roman era and the islands have been inhabited for at least 8500 years, originally occupied by Mesolithic and Neolithic tribes and then by the Picts. Orkney was invaded and forcibly annexed by Norway in 875 and settled by the Norse. The Scottish Parliament then re-annexed the earldom to the Scottish Crown in 1472, following the failed payment of a dowry for James III's bride Margaret of Denmark. Orkney contains some of the oldest and best-preserved Neolithic sites in Europe, and the "Heart of Neolithic Orkney" is a designated UNESCO World Heritage Site.