Most buildings can only be built within your own territory, marked by colored borders on the ground. Players can expand their territory by constructing buildings near their borders. (Some types of buildings will expand your territory more than others.) Borders may change throughout the game, based upon the buildings built and destroyed by the players.
If one of a player’s buildings falls into enemy territory due to shifting borders, then the building will slowly lose loyalty until finally converting to the enemy’s side. This can be stopped and slowly reversed if the border shifts and the building comes back to the player’s side.
There are a few important exceptions to this rule:
- Outposts, Docks and Roman Entrenched Army Camps can be built outside your borders, but none of these will gain you new territory;
- The Civil Center can be built either on your territory or on unclaimed territory, but must be built a certain distance away from your existing civil centers. Building a civil center can gain you lots of extra territory. Moreover, as you progress through different phases of the game (see “Technologies and Game Phases”), the territory controlled by your Civic Centers will expand by a small amount.
Docks do not lose loyalty/health outside your territory, but Outposts and Roman Entrenched Army Camps do. Roman Entrenched Army Camps can also be built in enemy territory.