Merseyside is comprised of five metropolitan boroughs: Knowsley, St Helens, Sefton, Wirral, and the city of Liverpool; it takes its name from the central River Mersey. Spanning 249 square miles of land, it borders Lancashire, Greater Manchester, Cheshire and the Irish Sea to the west; North Wales is across the Dee Estuary. There is a mix of high density urban areas, suburbs, semi-rural and rural locations in Merseyside, but the majority land use is urban. Its business district nucleus is formed by Liverpool city centre and is in the top five most populous conurbations in England, dominating the geographic centre of the county. Merseyside is an amalgamation of 22 former local government district counties of Lancashire, Cheshire and six autonomous county boroughs centred on Birkenhead, Bootle, Liverpool,Southport, St Helens, and Wallasey.