Einstein is half-right - but actually quite wrong! (Sorry Einstein). It isn't Westminster but the City Of London that is a mile square (which is why it's also known as... the Square Mile!). London -- the great, heaving metropolis of over 7million people -- is huge in area as well as population. It consists of 33 local government authorities, most of them called boroughs (Kensington & Chelsea, Islington, Barnet, Bromley etc etc) as well as the City of Westminster (includes Parliament, Buckingham Palace, much of the West End) and the City of London (east of Westminster, also on the north bank of the Thames, centred around St Pauls Cathedral). It includes most of 'the City', London's financial district. The Corporation of London, which is over 800 years old and was a model for parliament itself, is the local government authority; the City also has it's own mayor (Dick Whittington held this post) and police force. In other words, while it's understandably easy to confuse the two, 'London' and the 'City of London' are quite distinct places!