The City of London 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') or 'the Square Mile' as it is 1.12 square miles 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 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, ranking as the world's leading centre of global finance. Throughout the 19th century, the City was the world's primary business centre, and continues to be a major meeting point for businesses.
The City had a resident population of about 7000 in 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.