Many people ask me about the City of London.  I think very few people understand the true significance of the City and its History. The small, ancient City of London at its core once contained the whole settlement, but as the urban area grew the City resisted attempts to amalgamate it with its suburbs. 40% of Greater London is covered by the London "postal district", within which London forms part of postal addresses. The London telephone area code covers a larger area, similar in size to Greater London, although some outer districts are omitted and some places just outside are included.

 The area within the orbital motorway is sometimes used to define the London area and the Greater London boundary has been aligned to it in places.  Urban expansion is now restrained by a metropolitan green belt, although the built up area extends far beyond the boundary in places, resulting in a separately-defined Greater London Urban Area. Beyond this is the vast London commuter belt. In addition, the City is split by the River Thames into North and South, with an informal Central London area at its core.