Whan it has a seat----------------A City is a City when it is INCORPORATED....essentially, it then becomes a Buisness It makes money through taxes (property, Sales, etc.) otherwise, an area not...
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A city is a city because it was one the the important places in the world.
The plural form of city is cities.
A city state within a city is Vatican City which is located withing the city of Rome, Italy. Rome is a landlocked city.