London is a world unto itself, and it has been for most of its very, very long history. One of the weirdest things about the city is that it contains its own separate city – distinct from the rest of London. It has its own laws, its own government, its own walls. The City of London is a city within a city.
And it gets a lot of attention, not to mention money. Currently it houses the financial district which houses the most powerful banking institutions of not only the UK, but the entire world.