Kinder Scout, at 636 metres (2,087 ft), is the highest point in the county, whilst Trent Meadows, where the River Trent leaves Derbyshire, is its lowest point at 27 metres (89 ft). The River Derwent is the county's longest river at 66 miles (106 km), and runs roughly north to south through the county. In 2003 the Ordnance Survey placed Church Flatts Farm at Coton in the Elms (near Swadlincote) as the farthest point from the sea in Great Britain. The city of Derby is a unitary authority area, but remains part of the ceremonial county of Derbyshire. The non-metropolitan county contains 30 towns with 10,000–100,000 inhabitants. There is much sparsely populated agricultural upland.