The Sentry Tower is a defensive structure available once the Bronze Age is reached. It is also available to the Scenario Editor and can be seen throughout the Campaign mode of the game. It is an upgrade of the Watch Tower and can be researched in the Granary for 120 food and 50 stone. Every civilization in the game have the ability to construct this Tower. Like all towers, Sentry Towers are more resistant against stone throwing siege weapons unlike other buildings, having 18 additional siege armor against them after accounting for building armor. Against Armored Elephants, Sentry Towers have 16 extra armor.