"London" now refers to Greater London, which is made up of 32 boroughs (including the City of Westminster and the City of London. The City is in central London and is the oldest part of the city, dating back to Roman times. The City of London has its own mayor, the Lord Mayor of London, an office separate from (and much older than) the Mayor of London. There are other ancient features, dating back to medieval times. The City has its own police force, the City of London Police.