Any city that had started off as a small settlement on the bank of a river in medieval times had to grow exponentially and so did the City of London on the Thames riverside. The original city that is known as City of London does not exactly refer to the place known around the world as London. It is a patch of ground measuring around one square mile on a rough estimate and was built by the Roman settlers of yore. Gradually it came to be known as the Square Mile or The City. It had a wall 18 feet high and there was a moat surrounding it. There are no traces of either of them at present, having been encroached upon and destroyed by the burgeoning population and the commercial activities that they engaged themselves in. The relentless expansion went on for centuries and the area grew not only into the financial capital of England but as the most influential financial center in the world in deed.
Though it is now an indistinguishable part of London, the name "Square Mile" stuck along with the other name "The City" and still serves as a popular reference point. International banks of all descriptions, financial institutions and major businesses can all be found here. It is quite a prestigious destination for any business worth its salt to flaunt its office here.
How serious its importance is viewed by the London administration can be gauged by the fact that the Metropolitan Police does not have its jurisdiction over the City of London and is catered to by its own police force. Resemblance to Vatican, a state within state, may not be overtly felt but there are some striking similarities. The City has its own coat of arms. A Lord Mayor is elected every year and he is the one who is in charge of every aspect of administration within the Squire Mile. Second only to British throne, the mayor of the City of London is the oldest authority in England.