It seems that in most countries of the world there is one city that dominates the rest population wise, economically, and culturally. These cities are often the only city of a country known by foreigners. And there is no doubt that there are a lot of them: London, Tokyo, Toronto, Mexico City, Panama City, Bogotá, Santiago, Buenos Aires, Paris, Madrid, Oslo, Stockholm, Helsinki, Moscow, Cairo, and more.
In fact, some cities are so dominant that it could be said that the country is actually a city state. A city state is defined as a state consisting of one city. But how big of a city does it need to be to count as one? Some countries, like Luxembourg and Singapore, are known as city states. Some countries are not known as city states, but they have a city that overwhelmingly exceeds the rest. Some of these countries include Belgium, with its capital Brussels producing 59% of the economic output of the country. Another is Denmark, with Copenhagen producing 55% of the economic output. These countries could potentially be called city states, but since the definition of city state is so ambiguous, we will never no for sure.