The City of London is a geographically small city within Greater London in England. It is the historic core of London around which, along with Southwark and then Westminster, the modern conurbation grew. The City’s boundaries have remained almost constant since the Middle Ages, and hence it is now only a tiny part of the much larger London metropolis. It is often referred to as the City or the Square Mile, as it is just over one square mile (1.12 mile² / 2.90 km²) in area. These terms are also often used as metonymies for the United Kingdom's financial services industry, which is based here.
In the medieval period, the City was the full extent of London. The term London now refers to a much larger conurbation containing both the City of London itself and the 32 London boroughs, constituting Greater London. The City is today a major business and financial centre, ranking on a par with New York City as the leading centre of global finance; in the 19th Century, the City served as the world's primary business centre. The City has a resident population of under 10,000, whilst it employs 340,000 professional workers, mainly in the financial sector, making the area's transport system extremely busy during peak times.
The City is not one of the 32 London boroughs. It is governed by the City of London Corporation, which has some unusual responsibilities for a local authority, such as being the police authority for the City. It also has responsibilities and ownerships beyond the City's boundaries.
Area : 1,579 km2 (609 sq mi).
Number of inhabitants : 7,512,400 (mid-2006.
Density of population : 4,758 people /km2.