What is the City of London? The term is in everyday use but few are willing to define it. If pressed some will suggest that it means the entire UK financial sector while others point to a particular part of London - the Square Mile. Neither of these definitions is adequate because the City is both greater and less than either finance alone or a physical location. The author demonstrates that it is only by taking a detailed look at the City over the last 100 years that it can be understood.