Trench

The trench provides shelter for a single infantry unit. Units inside can still attack, and are protected from most types of damage until the trench is destroyed. They are still vulnerable to three types of damage however: bayonet (from riflemen), high explosives (from mortars, howitzers, and battleships), and gas (from howitzer). Enemy units are significantly slowed when walking over trenches. Infantry units can get in enemy trenches if they are empty, capturing it for themselves.

Railroad

Railroads provide a movement speed bonus to nearby allied units, as long as they are out of combat. This bonus is especially important for slow units such as howitzers and railway guns.

Barracks

The barracks can train infantry units; workers, riflemen, machines guns, and mortars.

Factory

The factory can train three types of artillery; field guns, howitzers, and railway guns, as well as tanks, airplanes, and observation balloons. Both tanks and railway guns must be researched before they can be built.

Machine Shop

The machine shop can repair up to three nearby factory units at once. Units must be out of combat to be healed.

Hospital

The hospital can heal up to six nearby infantry units at once. Units must be out of combat to be healed.

Fortress

The fortress is a versatile defense structure, with more range than infantry, but less range than artillery. They are most effective vs units with lots of armour, such as tanks and ships.

City

Cities are settlements that provide 30 income per month when at full population. Cities can build workers and spawn militia when above 20% population.

Capitol

Cities are large settlements that provide 60 income per month when at full population. Capitols can build workers and spawn militia when above 20% population.

Town

Towns are small settlements that provide 15 income per month when at full population. Towns can build workers when above 20% life.

Port

Ports are small coastal settlements that provide 15 income per month when at full population. Ports can build and repair naval units when above 20% life. Ships can be repaired two at a time, and must be out of combat.