Simply put, these would be recurring wonders you could build multiple times. Examples: Crusade Requirements: Must be a holy city. Effect: Choose one civilization with a rival state religion. All civs with state religion of city declare war on that civilization. Great Exhibition Requirements: Must have a Market, Harbor and Theater. Effect: One free trade route in city to capital of each other civ for <X> turns. Olympiad Requirements: Must have a Stadium, Airport and Coliseum in city. Effect: No happiness penalties in your civ for <X> turns, ends all wars for <X> turns.