The City of London, widely referred to simply as the City, is a city, ceremonial county and local government district that contains the ancient centre, and constitutes, along with Canary Wharf, the primary central business district (CBD) of London and one of the leading financial centres of the world. It constituted most of London from its settlement by the Romans in the 1st century AD to the Middle Ages, but the modern area referred to as London has since grown far beyond the City of London boundary. The City is now only a small part of the metropolis of Greater London, though it remains a notable part of central London. The City of London is not one of the London boroughs, a status reserved for the other 32 districts. It is also a separate ceremonial county, being an enclave surrounded by Greater London, and is the smallest ceremonial county in England.

Canary Wharf is an area of London, England, located near the Isle of Dogs in the London Borough of Tower Hamlets. Canary Wharf is defined by the Greater London Authority as being part of London's central business district, alongside Central London. Alongside the City of London, it constitutes one of the main financial centres in the United Kingdom and the world, containing many high-rise buildings including the third-tallest in the UK, One Canada Square, which opened on 26 August 1991.