The City of London is a district of 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, though it remains a notable part of central London. The City holds city status in its own right, and is also a separate ceremonial county.

It is often referred to as the City (often written on maps as City) or the Square Mile, as it is just over one square mile 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 based in the City.

The term London now refers to a much larger conurbation roughly corresponding to the London region, which i...