Cornwall is a county in South West England in the United Kingdom. The county is bordered to the north and west by the Celtic Sea, to the south by the English Channel, and to the east by the county of Devon, over the River Tamar which forms most of the border between them. Cornwall forms the westernmost part of the South West Peninsula of the island of Great Britain. The furthest southwestern point of Great Britain is Land's End; the southernmost point is Lizard Point. Cornwall has a population of 563,600 and covers an area of 3,563 km² (1,376 sq mi). The county has been administered since 2009 by the unitary authority, Cornwall Council. The ceremonial county of Cornwall also includes the Isles of Scilly, which are administered separately. The administrative centre of Cornwall, and its only city, is Truro.