A city is usually thought of by geographers as a place which is home to large numbers of people, perhaps half a million or more. It is a place with important buildings like a city hall, and it has large shopping streets and suburbs. However, cities can mean other kinds of places, too. In Britain, cities used to be places where there was a cathedral. This was so even though the places might be tiny, like St Davids in Wales. This is not a very useful definition of a city. In the United States, some places choose to call themselves city even if they are tiny.