Sister cities of City of London

The City of London is a city within London. The City constituted most of London from its settlement by the Romans in the 1st century AD to the Middle Ages, but the conurbation has since grown far beyond its borders. As the City's boundaries have remained almost unchanged since the Middle Ages, it is now only a tiny part of the metropolis of Greater London, though it remains a notable part of central London. It holds city status in its own right and is also a separate ceremonial county.

It is widely referred to as the City (often written on maps as "City" and differentiated from the phrase "the city of London" by capitalising the word City) or the Square Mile as it is 1.12 sq mi (2.90 km²) in area. These terms are also often used as metonyms for the United Kingdom's financial services industry, which continues a notable history of being largely based in the City.

The term London now refers to a much larger conurbation roughly corresponding to the London region, also known as the Greater London administrative area, comprising 32 boroughs (including the City of Westminster), in addition to the City of London. The local authority for the City, the City of London Corporation, is unique in the UK and has some unusual responsibilities for a local council, such as being the police authority. It also has responsibilities and ownerships beyond the City's boundaries. The Corporation is headed by the Lord Mayor of the City of London, an office separate from (and much older than) the Mayor of London.

The City is a major business and financial centre. Throughout the 19th century, the City was perhaps the world's primary business centre, and it continues to be a major meeting point for businesses. London came top in the Worldwide Centres of Commerce Index, published in 2008. The insurance industry is focused around the eastern side of the City. Another major financial district in London is located at Canary Wharf, 2.5 miles (4.0 km) to the east.

The City has a resident population of about 7,000 (2011) but over 300,000 people commute to it and work there, mainly in the financial services sector. The legal profession forms a major component of the northern and western sides of the City—especially in the Temple and Chancery Lane areas where the Inns of Court are located, of which two—Inner Temple and Middle Temple—fall within the City of London boundary.