Cornwall (Cornish: "Kernow") is a county in the far southwest of England in the United Kingdom. Truro is the capital of the Unitary Authority that has administered Cornwall since 2009. Truro is also the only city. It has the cathedral of the Diocese of Truro. Cornwall is home to the Cornish Language and the Cornish people. The Duchy of Cornwall is an estate which belongs to the Prince of Wales (who is also the Duke of Cornwall), but only part of it is in Cornwall. Cornwall is split from Devon by the River Tamar.