Peterborough ( (listen)) is a cathedral city in Cambridgeshire, east of England. It is the largest part of the City of Peterborough unitary authority district (which covers a larger area than Peterborough itself). It was part of Northamptonshire until 1974, when county boundary change meant the city became part of Cambridgeshire instead. The city is 76 mi (122 km) north of London, on the River Nene which flows into the North Sea 30 mi (48 km) to the north-east. In 2020 the built-up area subdivision had an estimated population of 179,349. In 2011 the district had a population of 183,631.
The local topography is flat, and in some places, the land lies below sea level, for example in parts of the Fens to the east of Peterborough. Human settlement in the area began before the Bronze Age, as can be seen at the Flag Fen archaeological site to the east of the current city centre, also with evidence of Roman occupation.