Ireland or Éire, officially the Republic of Ireland, is a country in western Europe. Lying off the north-western coast of the European mainland, the Republic of Ireland occupies about five-sixths of the island of Ireland. The state shares its only land border with Northern Ireland, a part of the United Kingdom. It is otherwise surrounded by the Atlantic Ocean, with the Celtic Sea to the south, Saint George's Channel to the south-east, and the Irish Sea to the east. The capital and largest city is Dublin, located on the eastern coast.