Peterborough is a cathedral city and unitary authority area in the East of England, with a population estimated to be 184,500 in mid–2011. Although traditionally part of Northamptonshire, for ceremonial purposes it falls within the county of Cambridgeshire. Situated north of London, the city stands on the River Nene which flows into the North Sea approximately to the north-east. The railway station is an important stop on the East Coast Main Line between London and Edinburgh. The unitary authority borders Northamptonshire and Rutland to the west, Lincolnshire to the north, and non-metropolitan Cambridgeshire to the south and east.