London Underground ticketing destinations and most interchange stations are in zone 1, meaning that most journeys over similar distances will cost the same. A few stations in the north east of the network, on the Central line, outside Greater London (in the Epping Forest district) are in zones 4, 5 and 6. In the north west of the network, on the Metropolitan line, zones 7, 8 and 9 (formerly A - D) cover stations outside Greater London including Amersham and Chesham in the Chiltern district of Buckinghamshire. Unlike the lower numbered zones, these ancillary areas do not encircle the capital. Some stations are
London commuter belt East and South East regions. Most districts are entirely, or have sections, within the M25 motorway or are within of Charing Cross. Adjacent districts often share characteristics of Outer London, such as forming part of the continuous urban sprawl, being served by the London Underground, being covered by the London telephone area code, (until 2000) forming part of the Metropolitan Police District and having a relatively high employed population working in London. Larger Urban Zone is a definition created by Eurostat that measures the population and expanse of metropolitan areas across European countries. The population of London's Larger Urban Zone