A city is an important strategic structure capable of generating gold and producing units. Larger cities can be upgraded to produce more gold and more powerful units.
Each city is populated by a particular race and a leader's race relations plays an important role in how the city's population responds to being conquered. The sentiment of the population towards its leader is called its city morale. Friendly cities may offer to join and hostile populations may revolt against new leadership.
The leader of a city may chose one of six different projects for the city to work on including producing gold or units, constructing improvements, or even destroying the city itself.