Orkney also known as the Orkney Islands, is an archipelago off the north coast of Great Britain, 16 kilometres (10 mi) north of the coast of Caithness. Orkney comprises approximately 70 islands, of which 20 are inhabited. The largest island, Mainland, often referred to as "the Mainland", has an area of 523.25 square kilometres (202 sq mi), making it the sixth largest Scottish island and the tenth-largest island in the British Isles. The largest settlement and administrative centre is Kirkwall.