Cities

City sites
City sites are the only locations where Settlers can found new Cities. A city site can be claimed by a nation by moving a Unity onto it.

Barbarians
Barbarians occupy City-States like other Tribes, but they are in a permanent state of War with all Nations. They have a number of special units: Marauders, Skirmishers, Elite Marauders and Elite Skirmishers.

Improvements
Improvements can be used to grand various bonuses to a City. There are two types of improvements: rural and urban.

Rural improvements
Rural improvements may be built on any non-urban tile. Tiles where Rural improvements may be constructed will show the improvement with an icon above if a Worker is currently standing on the tile.

Urban improvements
Urban improvements expand the urban area of a city by transforming the terrain underneath to Urban.