Keep

The Keep is the upgrade of the Guard Tower, and is the highest level of arrow-firing tower available (the Bombard Tower is a more powerful but slower-firing cannon-firing tower, however, the two towers are unrelated and available simultaneously to the player).

Upgrading to Keep is expensive, and rarely pays off as it is only a negligable improvement on the Guard Tower. They are only avaliable to Britons, Byzantines, Celts, Chinese, Japanese, Koreans, Maya, Saracens, Spanish, Teutons and Turks.

Garrisoned foot archers and villagers will increase the number of arrows the tower fires, thus increasing the damage. Up to five foot-soldiers (infantry and archers, although infantry do not increase the firepower of the tower) may be garrisoned into the watch tower. When garrisoned in the keep (or any other building) units will slowly regain any lost hit points. This ability can be sped up by researching Herbal Medicine.

Offensively, towers can be upgraded by Fletching, Bodkin Arrow, and Bracer (all Blacksmith upgrades) for range and damage, Chemistry (at the University) for damage, and Heated Shot (also at the University) for damage against ships. Defensively, towers may be upgraded with Masonry, Architecture (increase HP), and Murder Holes (eliminates minimum range). Towers are generally more useful in the game for stopping and slowing small raiding parties. They are ineffective against large armies and siege weapons.

Civilization Bonuses

 * Teutons: Keeps can garrison at most 10 Archers or Infantry units at one time. This also doubles the maximum number of arrows that can be fired. A fully garrisoned Teutonic Keep can fire as many as eight arrows, dealing up to 80 damage if it is fully upgraded. Imperial age unique technology Crenellations allows garrisoned infantry to fire arrows.
 * Koreans: Keeps have additional range by one point from Castle Age beyond. In addition, Korean towers upgrades itself automatically from Castle Age to Imperial Age. If all technologies are researched, Korean Keeps can have as many as 13 range points. This range bonus makes Bombard Cannons and Cannon Galleons ineffective against them. However, a Turkish Bombard Cannon and Cannon Galleon with Artillery researched can out range a Korean Guard Tower.
 * Britons: Imperial Age unique technology Yeomen, adds +2 attack to Keeps.
 * Byzantines: Keeps have 10%/20%/30%/40% more Hit Points in Dark/Feudal/Castle/Imperial age. Town Watch upgrade is free.
 * Spanish: Keeps are built 30% faster.
 * Chinese :Technologies that benefits Keeps are 10%/15%/20% cheaper in Feudal/Castle/Imperial age.

The Forgotten Changes



 * Keeps get +1 attack
 * Koreans: Build Keeps and other defensive structures 25% faster.
 * Japanese: Castle age Technology Yasama allows their Keeps to fire extra arrows.
 * Chinese : Castle age technology Great Wall improves the Keeps hitpoints (+30%hp)
 * Celts Castle age technology Stronghold : Improves the firing rate of Keeps.
 * Incas: 15% stone discount on buildings applies to Keeps.
 * Britons: Yeomen technology moved to Castle age, adds +2 attack to Keeps.

Overview
''The central and strongest building inside a castle was called the keep. This was the last bastion of defense inside if the walls and outside towers were taken. The remaining defenders withdrew into the keep for the final defense. The keep was a mini-castle often constructed in place of a castle to cut expenses. Although much smaller than castles, keeps could perform the same function on a smaller scale. They were very difficult to capture except by a large and well-equipped army.''