General:
* City
* Metropolitan
* Municipal
* Town
* Civic
* Developed
* Populated
* Built-up
More specific:
* Conurbation (a densely populated area)
* Metropolis (a large, important city)
* Downtown (the central business district of a city)
* Inner city (the older, more densely populated part of a city)
* Suburban (relating to the outskirts of a city)
The best synonym will depend on the specific context in which you are using it.