The City of London is a city, ceremonial county and local government district in England. Established by the Romans around 47 AD as Londinium, it forms the historic centre of the wider London metropolis. Surrounded by the modern ceremonial county of Greater London, from which it remains separate, the City is a unique local authority area governed by the City of London Corporation, which is led by the Lord Mayor of London, though it is included as part of the region of England governed by the Greater London Authority.