National Wonder. Can only be built once in your empire. To unlock: Requires that you are at War with other Civilizations. Must be built adjacent to an Encampment district.

Provides the same defensive bonuses as the Fort improvement. Grant Walls and Medieval Walls in this City. Promoting a unit does not end that unit's turn. +4 Combat Strength for all military units in your territory. All buildings in Encampment districts provide +2 Production and +2 Culture. +100% Encampment district Production adjacency bonuses. Military Engineers gets +1 Movement and +1 build charge. Fort improvements provide Tourism from Culture after researching Flight.

+2 Tourism
+1 extra per Era that you've advanced past this Wonder's era