Peterborough (/ˈpiːtərbərə, -ˌbʌrə/) 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 2021 the Unitary Authority area had a population of 215,671. 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 and to the south 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. The Anglo-Saxon period saw the establishment of a monastery, Medeshamstede, which later became Peterborough Cathedral. The population grew rapidly after the railways arrived in the 19th century, and Peterborough became an industrial centre, particularly known for its brick manufacture. After the Second World War, growth was limited until designation as a New Town in the 1960s. Housing and population are expanding and a £1-billion regeneration of the city centre and immediately surrounding area is under way. Industrial employment has fallen since then, a significant proportion of new jobs being in financial services and distribution.