The cities you build provide the foundation for your great empire. They allow you to expand your national borders, collect more resources, and build citizens. The number of cities you can build is dependant on the amount of civics research you have done.

The library is where you conduct research in four main areas (Military, Civic, Commerce, and Science), as well as research for advancing in ages.

Your markets are where Caravans and Merchants are trained, which allow you to collect wealth and the bonuses from rare resources. With the appropriate commerce research, you can also buy and sell resources at the market.

Temples allow you to expand the borders of the cities they are constructed in. You can also conduct research into taxation, which allows you to collect wealth based on the territory you control.

The university is the sole place where you can collect Knowledge. Each university can hold up to seven scholars that generate knowledge.

Woodcutter's camps are built near collection trees, and collect Timber when citizens are assigned to work at them. The number of citizens each camp can hold is dependant on the number of trees nearby.

Mines are built next to mountains and generate metal depending on the number of citizens assigned to work there. Each mountain can only support one mine.

Starting in the Industrial Age, oil will appear on the map on rocky areas and in the sea. Your citizens can build oil wells and oil platforms on these deposits to collect oil, which becomes an invaluable resource in the later stages of the game. Each well/platform supports one citizen.

The granary is a resource enhancement building that allows you to increase the Food production of the farms in the city that it is constructed in. It also allows you to perform research to upgrade your infantry, cavalry, and ships.

The lumber mill is a resource enhancement building that allows you to increase the Timber production of the woodcutter's camps in the city that it is constructed in. It also allows you to perform research to upgrade your vehicle upgrade speed and attrition damage.

The refinery is a resource enhancement building that allows you to increase the Oil production of all oil wells in your nation.

The smelter is a resource enhancement building that allows you to increase the Metal production of the mines in the city that it is constructed in. It also allows you to perform research to upgrade your units' stats.

The barracks is where you construct all your foot units, from primitive slingers and bowmen to modern assault infantry and flamethrowers.

The stable is where you construct your cavalry units, including knights and horse archers. In the industrial age, it becomes an Auto Plant, where you can construct tanks and armored cars.

The siege factory, and later the factory, is where your siege units - from catapults to howitzers - and supply wagons are created.

The dock is where all naval units - fishermen, triremes, aircraft carriers, and battleships - are constructed.

Your airbases house fighters and bombers, and can construct helicopters as well. In the event of an emergency, you can scramble your planes at an airbase, and they will attack any nearby enemies.

Each missile silo can store either one traditional missile, or one nuclear missile.

Your forts provide a solid defensive structure that also expands your national borders. It is also where you can train spies and generals.

Your towers provide defense against oncoming enemy troops. Units can also garrison inside of them.

At the game's outset, lookouts are defenseless structures that provide a large viewing radius. By the industrial age, they turn into Air Defense sites and are essential for protecting your nation against air raids.