What is the smallest city in your country that everyone can still instantly recognise the name of? What is it famous for?
In the United States, I'd probably name Oregon City, the famous end of the Oregon Trail and the first city founded west of the Rocky Mountains during the pioneer era. Its population is only 37,000.
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.