Great people improvement
Great tile improvement. Constructed by a Great General.
- Connects any strategic resource on the tile.
- +100% Defensive Combat Strength for a unit on the tile.
- Damages all enemy units that end their turn on an adjacent tile for 30% of their maximum HP. (Damage does not stack with other Citadels.)
- Instantly annexes all nearby tiles into your empire's territory. (Must be constructed on a tile within or bordering your own territory. Will NOT annex an enemy city if placed adjacent to it, but will damage all units within it, including aircraft.)
Citadels have a variety of strategic uses, both during war and times of peace. Place Citadels at choke points in terrain to defend your borders, forcing would-be attackers to either suffer heavy losses or attack from a less direct path.
Outside of war, Citadels can be used to immediately acquire neighboring land tiles that contain a variety of important resources. This essentially allows you to steal strategic or luxury resources from either an enemy civilization or a nearby city-state. Stealing land from enemy civilizations causes them to become more aggressive, so stealing from a more powerful opponent isn't advisable. On the other hand, stealing from city-states only incurs an influence decrease and doesn't seem to anger their allies.
Citadels in wartime will continue to cause automatic damage to enemy units, even if those enemy units are inside the Citadel or an adjacent city. They are still susceptible to enemy pillaging, however.
You cannot place your own Citadel over top of an existing citadel in foreign territory, even if it's adjacent to your own borders.
A Citadel is a mighty fortification that can only be constructed by a Great General, usually near a city or on a particularly defensible piece of terrain. The Acropolis in Athens, Greece, is an example of an early powerful Citadel. Such structures were almost impossible to take by direct attack, and they were capable of withstanding protracted sieges before they fell. You can construct a Citadel anywhere within your territory, or directly adjacent to your territory. Upon constructing the Citadel, your Culture borders will also expand to surround the Citadel on all sides by one hex. If the new Culture border claims hexes already owned by another civilization, you will incur a diplomatic penalty as a result. Any unit stationed within a Citadel receives a 100% defensive strength bonus. Additionally, any enemy unit which ends its turn next to a Citadel takes 30 damage (damage does not stack with other Citadels).