In the UK it's got to be the City of London. Famous for being an ancient city established by the Romans and awash with history, now one of the world's biggest financial centers with a modern skyline of famously distinctive skyscrapers. It's home to some world-famous landmarks like Saint Paul's Cathedral and Tower Bridge, and has a population of about 10,000.
The City of London is not to be confused with London, London, London or London.
I know, right? Why deal with Problem X when Problem Y also exists?