Forts are buildings that can be constructed in provinces. They have several benefits:

• A fort is required to recruit most national units in a province
• Forts add additional commander points to the provinces they are built in
• You can only collect income from a province if you can trace a path from it to a friendly fort (usually)
• Enemy armies that conquer a province with a fort do not automatically capture it; they must first besiege it and destroy the walls before storming it.
• Forts increase the income of the provinces they are built in by a percentage equal to half of their administration value
• Forts draw resources from adjacent provinces; the percentage is equal to the administration value of the fort
• Forts provide bonus supply to their province and nearby friendly provinces

Unlike labs and temples, they take multiple turns to build.

Once they are built, they may be upgraded (again taking several turns and some gold). The standard upgrade path is Palisade → Fortress → Castle → Citadel → Grand Citadel, although few nations can upgrade all the way. Each upgrade adds to the wall integrity in a siege and administration value. Additionally, Fortresses and Castles provide +1 commander point, and Citadels and Grand Citadels provide +2.

Most Early Age nations can only build up to their second tier of fort, most Middle Age nations can only build up to their third tier of fort, and most Late Age nations can only build up to their fourth tier of fort. Commanders with the Mason trait can upgrade a fortification to be one tier higher than what's usually available to their nation (for example, Early Age Arcoscephale's Engineers can upgrade Fortresses into Castles).

Some nations have different upgrade paths; nations that can build underwater forts may have different upgrade paths underwater.

Image	Name	Build Cost/Turns	Admin	Command Point Bonus	Recruitment Point Bonus	Supply Storage	Wall Integrity
	Palisades	600/4	15	0	50%	100	100
	Fortress	300/2	30	1	75%	500	250
	Castle	300/2	45	1	100%	1500	500
	Citadel	450/3	60	2	125%	5000	750
	Grand Citadel	600/4	70	2	150%	7500	1000

Most nations that have Primitive Forts are one tier behind most of their competitors – for example, EA Yomi can't build Fortresses. EA Rus, on the other hand, gets "Primitive" Forts, wooden varieties of the standard upgradable forts that never quite reach a Fortress's level of defense (they always have the Palisades icon) but still get the Commander Point bonus. These forts are 25% cheaper than the equivalent "non-Primitive" versions.

EA Mekone can build them; EA Ermor and some other nations start with one on their capital, but cannot build them.

Mictlan gets to build "Primitive" Fortified Cities.

EA Hinnom gets to build Giant Forts, which