Building Wonders contributes towards satisfying the requirements for being able to build the United nations, while amassing 20,000 gold qualifies one to build the World Bank. Being the first to finish building the United Nations or the World Bank will win the game, (Cultural and Economic victories).
They can also offer military benefits to the players by granting certain bonuses in addition to expanding the civilization. The Great Wall Wonder forces all other civilizations to offer peace to you until another civilization discovers Engineering. The Samurai Castle gives the owner's forces a +1 bonus to their attack, (+3 for an army, which is 3 units). Hollywood stops City Walls from preventing opposing civilization's cities from flipping, (switching sides), while still allowing the owner's city walls to function in this aspect. Building wonders will add towards qualifying to be able to have a Culture win. A total of 20 Great people, switched cities and wonders are required before the United Nations can be built. The United Nations is also a wonder but doesn't count towards the total required. This is one of the four ways to win Civilization Revolution.
Since wonders require many turns worth of resources, especially early in the game, they can be a handy way to bank production points. Simply switch to another use before the wonder is completed.
Timing the completion of wonders such as Leonardo's Workshop can be very important. Built too soon, the unit upgrades will be less than impressive.
- If another civilization finishes construction of a wonder you are building, the notification that nothing has been selected for construction in that city will come up. The production points already generated for building the wonder are not lost, however, and will be credited towards whatever is designated next.
- If a Wonder, such as the Manhattan Project, is in a city that is flipped to the player, the Wonder no longer functions, (it will show up in the list of buildings in that city, though).