Wonders are special buildings which can each be completed by only one player each game, and which often enhance their entire civilization. Unlike ordinary city improvements, which must be built with local production points, certain special units built in one city (Caravans and Freight) can contribute their full cost in production points towards the construction of a wonder in another city.
Once built, a wonder is placed in the city that constructed it, and cannot be sold or destroyed (unless the entire city is destroyed). However, some wonders are made obsolete under certain circumstances, and lose their effect. Note the asymmetry: while you must personally achieve the advance required by each wonder to build it, it will be disabled when any player achieves the obsoleting advance.
The entire map becomes permanently visible to the player who owns it -- the player always has up-to-date knowledge of all terrain and cities (but not units) despite fog-of-war. It allows all players to start building spaceship parts (assuming they have researched the necessary technologies).
Completion of the Apollo Program also allows nuclear-armed powers to declare war without provocation, regardless of the existence of the United Nations, and AI players will no longer be friendly towards the owner of the United Nations or the Eiffel Tower.
Requires knowledge of the technology Space Flight.
In every city with a Stock Exchange, city improvements which would normally have an upkeep of 1 become free of upkeep. (Communist governments inherently give this benefit, so there is no bonus under Communism.)
Upon completion of this wonder, tax collector specialists' gold output increases to 3 permanently for every nation.
Requires knowledge of the technology Economics.
Requires Stock Exchange in the city.
Each tile around the city where this wonder is built that is already generating some trade produces one extra trade resource.
Requires knowledge of the technology Bronze Working.
* The discovery of Automobile will make it obsolete.
Each tile worked by the city where this wonder is built produces one extra research point.
Requires knowledge of the technology Astronomy.
* The discovery of Computers will make it obsolete.
This stunning technological achievement makes one content citizen happy in each of your cities (2 extra luxury per city). It further reduces your risk of plague (by 10% of the base chance); with knowledge of Medicine, any of your cities with an Aqueduct and a Sewer System will be entirely free of plague.
Requires knowledge of the technology Genetic Engineering.
Charles Darwin's voyage sparked the discovery of the evolution of the species, which inspired greater confidence in science. All your cities generate 1 extra science bulb.
Upon completion of this wonder, scientist specialists' research output increases to 3 permanently for every nation.
Requires knowledge of the technology Steam Engine.
AI nations are more inclined to be friendly and forgiving toward the owner of this wonder (until the Apollo Program is completed). It also reduces the pollution caused by the population; it counteracts the pollution associated with a single building in each of your cities.
Requires knowledge of the technology Railroad.
Gives an immediate technology advance to the player that builds it, and thereafter 4 extra research points every turn to its city.
Completion of this wonder permanently doubles the effect of Libraries for every player.
Requires knowledge of the technology Literacy.
Requires Library in the city.
Increases the defense of all your cities by adding a +50% bonus to its units' intrinsic defense strength against land units (this is cumulative with any City Walls), and preventing the loss of population which occurs when a defending unit is defeated by a land unit.
Requires knowledge of the technology Construction.
* The discovery of Machine Tools will make it obsolete.
Makes one unhappy citizen content in every city of the player that owns it (not including citizens unhappy about aggression). This wonder also makes two content citizens happy in the city where it is located (4 extra luxury points).
Requires knowledge of the technology Pottery.
* The discovery of Electricity will make it obsolete.
Acts as a Hydro Plant in the city where it is built, and reduces pollution from shield production by a further 25% in all cities with Hydro Plants, making them equivalent to Solar Plants.
Requires knowledge of the technology Electronics.
Requires River on the tile or an adjacent tile.
Requires Factory in the city.
Gives an immediate technology advance to the player that builds it, and thereafter 6 extra research points every turn to its city.
Completion of this wonder permanently doubles the effect of Universities for every player.
Requires knowledge of the technology Theory of Gravity.
Requires University in the city.
Makes one content citizen happy in every city of the player that owns it (2 extra luxury points per city).
Requires knowledge of the technology Theology.
Reduces the unhappiness caused by aggressively deployed military units owned by the city by 1 -- in other words, it neutralizes the unhappiness caused by a single military unit (except under Democracy, where a single unit makes two citizens unhappy). Under governments where unit upkeep is paid in gold, it gives two free gold per city towards upkeep every turn.
Requires knowledge of the technology Chivalry.
* The discovery of Communism will make it obsolete.
Upgrades one obsolete unit per game turn.
Requires knowledge of the technology Invention.
* The discovery of Combustion will make it obsolete.
Gives all your sea units 1 additional movement point (except Triremes while moving on rivers). Makes all your new sea units veterans (for all your cities).
Requires knowledge of the technology Map Making.
Requires terrain with the 'Sea' flag on the tile or an adjacent tile.
* The discovery of Engineering will make it obsolete.
Gives all your sea units 1 additional movement point. The chance of a sea unit getting the next veteran level after a battle increases by half.
Requires knowledge of the technology Magnetism.
Requires terrain with the 'Sea' flag on the tile or an adjacent tile.
* The discovery of Nuclear Power will make it obsolete.
Requires knowledge of the technology Nuclear Fission.
* Allows all players with knowledge of Nuclear Fission to build units: Nuclear
The player who owns it gets an embassy with all players.
TIP: if you're behind in research, this can help you catch up, by reducing the cost of technologies that other players already know.
Requires knowledge of the technology Trade.
* The discovery of Democracy will make it obsolete.
Doubles the base effect of Cathedrals. This makes 3 additional unhappy citizens content in each city with a Cathedral; however, it does not affect citizens made unhappy by aggression.
Requires knowledge of the technology Monotheism.
Requires Cathedral in the city.
With this wonder, City Walls and Courthouses each make one unhappy citizen content in their city, unless that citizen is unhappy about aggression. Also, none of the owner's cities can be incited to revolt.
Requires knowledge of the technology Ceremonial Burial.
* The discovery of Sanitation will make it obsolete.
Reduces by 1 the unhappiness caused by one aggressively deployed military unit per city -- in other words, in each city it neutralizes the unhappiness caused by a single military unit (except under Democracy, where it just halves the unhappiness from that unit). Each city also avoids one shield of upkeep for units.
Requires knowledge of the technology Polytheism.
* The discovery of Conscription will make it obsolete.
Makes 2 additional unhappy citizens content in every city with a Temple. Does not affect citizens made unhappy by aggression.
Requires knowledge of the technology Mysticism.
Requires Temple in the city.
* The discovery of Theology will make it obsolete.
Each tile around the city where this wonder is built that is already generating some shield output produces one extra shield resource. Under Despotism or Tribal governments, the Pyramids cancel the penalty to worked tiles with output greater than 2 (for all kinds of output), as if all your cities were always celebrating.
Requires knowledge of the technology Masonry.
* The discovery of Railroad will make it obsolete.
Gives an immediate technology advance to the player that builds it, and thereafter all cities on the map are continuously visible to its owner despite fog-of-war.
Completion of this wonder permanently doubles the effect of Research Labs for every player.
Requires knowledge of the technology Computers.
Requires Research Lab in the city.
Gives 1 additional luxury to every city, and 6 luxuries to the city where it is located.
Upon completion of this wonder, entertainer specialists' luxury output increases to 3 permanently for every nation.
Requires knowledge of the technology Sanitation.
Allows you to choose any government, including those that have not yet been researched by your civilization, and without the transition period of Anarchy. It also allows unprovoked declaration of war regardless of any senate instituted by a Democracy or Federation government or by the United Nations.
Requires knowledge of the technology Democracy.
All your new military land units start with an additional veteran level (this is cumulative with any Barracks building in a city; with both, units are created as Hardened).
Requires knowledge of the technology Feudalism.
* The discovery of Mobile Warfare will make it obsolete.
Creates a world senate that prevents unprovoked declaration of war by any nuclear-capable nation (that is, any nation with knowledge of Nuclear Fission, once the Manhattan Project has been built). AI players are more inclined to be friendly and forgiving toward the owner of this wonder. These effects last until the Apollo Program is completed.
Also, if any player's city is in disorder for more than two turns in a row, that player's government falls (even for governments other than Republic and Democracy).
Requires knowledge of the technology Communism.
Neutralizes the unhappiness caused by one aggressively deployed military unit per city. Under Democracy, it additionally halves the unhappiness caused by military units (reducing it to the same level as a Republic).
Requires knowledge of the technology Conscription.