Essex is a ceremonial and administrative county in England in the United Kingdom and is the home county northeast of the city of London. It borders the counties of Suffolk and Cambridgeshire to the north, Hertfordshire to the west, Kent across the estuary of the River Thames to the south and London to the southwest. Essex County Council is the principal local authority for much of the county, sharing functions with 12 district and borough councils.The historic county can be considered the oldest as Wessex and Mercia were replaced for administration since before the Norman period and a vestige of the term Northumbria exists in Northumberland — Essex occupies the eastern portion of the pre-England Kingdom of Essex. Large swathes of the county which are closest to London are part of the Metropolitan Green Belt, which prohibits urban development in its green spaces. It is the location of the regionally significant Lakeside Shopping Centre and London Stansted Airport; and the new towns of Basildon and Harlow. Norfolk is a low-lying county in the East of England. It has borders with Lincolnshire to the west, Cambridgeshire to the west and southwest and Suffolk to the south. Its northern and eastern boundaries are the North Sea coast and to the north-west the county is bordered by The Wash. The city of Norwich is the county town at Norfolk which is fifth largest ceremonial county in England, with an area of 5,371 km² (2,074 sq mi). Of the 34 non-metropolitan English counties, Norfolk is the seventh most populous, with a population of 850,800 (mid 2008). However, as a largely rural county it has a low population density, 155 people per square kilometre (or 401 per square mile). Norfolk has about one-thirtieth the population density of central London, the tenth lowest density county in the country, with 38% of the county’s population living in the four major built up areas of Norwich (195,000), Great Yarmouth (67,000), King’s Lynn (41,000) and Thetford (22,000).