Cornwall (pronounce /ˈkɔrnwɒl/; Cornish: Kernow [ˈkɛrnɔʊ, ˈkɛɹnɔʊ]) is the most southwesterly county in England, United Kingdom, on the peninsula that lies to the west of the River Tamar. The administrative centre and only city is Truro. Cornwall covers an area of 1,376 square miles (3,563 km²), including the Isles of Scilly, located 28 miles (45 km) offshore. Cornwall has a population of 513,528, with a relatively low population density of 373 people per square mile (144 /km²).