Cities may be improved with a wide variety of buildings, each with a different effect. Each city may have only one of each improvement, and some improvements require others to have been built first.
It costs production points to build improvements, and once completed, many improvements require an upkeep of one or more gold pieces per turn. You may dismantle and sell an improvement, receiving one gold piece for each production point used in its construction, although you may only sell one improvement per city per turn. If a turn comes on which you cannot pay the upkeep on all of your improvements, some of them will be automatically sold; obviously this should be avoided as the improvements chosen might not be ones you would have preferred to sell.
Most improvements become available only when you achieve certain technologies, and some improvements can become obsolete, at which point they are automatically sold.
Allows a city to produce veteran air units (including helicopters and missiles). Also, damaged air units (again, including helicopters) which stay in town for one full turn without moving are completely restored.
Two cities with Airports can airlift one unit per turn (including aircraft). Airlifting instantly transports the unit from one city to another and will use all of the unit's movement points. A unit must have some movement points left to be airlifted, and cannot carry cargo.
Requires knowledge of the technology Radio.
Allows a city to grow larger than size 8. (A Sewer System is required for a city to grow larger than size 16.)
These larger cities enjoy increased defense (+50%) against both land and sea units; however, such large settlements have a small risk of fire, which can destroy buildings in the city.
Starting at size 5, growing cities incur an increasing risk of plague due to overcrowding; an Aqueduct reduces that base chance by 30%.
Building an Aqueduct in a city without access to a lake or river requires knowledge of Construction, and it costs more to build and maintain.
Requires knowledge of the technology Construction.
Prevented by River on the tile or any adjacent tile.
Prevented by Lake on the tile or any adjacent tile.
Allows a city to grow larger than size 8. (A Sewer System is required for a city to grow larger than size 16.)
These larger cities enjoy increased defense (+50%) against both land and sea units; however, such large settlements have a small risk of fire, which can destroy buildings in the city.
Starting at size 5, growing cities incur an increasing risk of plague due to overcrowding; an Aqueduct reduces that base chance by 30%.
Aqueducts in cities with access to a lake require no special technology and are cheap to build and maintain.
Requires Lake on the tile or an adjacent tile.
Allows a city to grow larger than size 8. (A Sewer System is required for a city to grow larger than size 16.)
These larger cities enjoy increased defense (+50%) against both land and sea units; however, such large settlements have a small risk of fire, which can destroy buildings in the city.
Starting at size 5, growing cities incur an increasing risk of plague due to overcrowding; an Aqueduct reduces that base chance by 30%.
Aqueducts in cities with access to a river require no special technology and are cheap to build and maintain.
Requires River on the tile or an adjacent tile.
Prevented by Lake on the tile or any adjacent tile.
Increases the luxury and tax output in a city by an additional 50%. With both a Bank and a Marketplace in a city, the total bonus is 100%.
Requires knowledge of the technology Banking.
Requires Marketplace in the city.
* Allows to build Stock Exchange (with Economics).
With a Barracks, each new land unit built in a city will automatically have Veteran status, which means that its attack and defense strengths are increased by 50%.
Also, damaged land units which stay in town for one full turn without moving are completely restored.
* The discovery of Gunpowder will make it obsolete.
* The presence of Barracks II in the city will make it obsolete.
* The presence of Barracks III in the city will make it obsolete.
With a Barracks, each new land unit built in a city will automatically have Veteran status, which means that its attack and defense strengths are increased by 50%.
Also, damaged land units which stay in town for one full turn without moving are completely restored.
Requires knowledge of the technology Gunpowder.
* The discovery of Mobile Warfare will make it obsolete.
* The presence of Barracks III in the city will make it obsolete.
With a Barracks, each new land unit built in a city will automatically have Veteran status, which means that its attack and defense strengths are increased by 50%.
Also, damaged land units which stay in town for one full turn without moving are completely restored.
Requires knowledge of the technology Mobile Warfare.
A Cathedral makes 3 unhappy citizens content in a city, making it easier to maintain order in that city; however, it does not affect citizens made unhappy by aggression. Knowledge of Theology increases the effect of a Cathedral, making an additional unhappy citizen content, except under Communism.
Requires knowledge of the technology Monotheism.
Requires Temple in the city.
* Allows to build Michelangelo's Chapel (with Monotheism).
City Walls make it easier to defend a city. They add a +100% bonus to the intrinsic defense strength of units within the city against land units (that is a two-thirds increase for small cities, or a one-half increase for cities larger than size 8), but are ineffective against airborne and sea units. City Walls also prevent the loss of population which occurs when a defending unit is defeated by a land unit.
Requires knowledge of the technology Masonry.
Gives a +100% bonus to the intrinsic defense strength of units within a city when defending against enemy ships. For small cities the defense strength is doubled by this improvement; for cities larger than size 8, it is increased by two-thirds.
Requires knowledge of the technology Navigation.
Requires Oceanic terrain on the tile or an adjacent tile.
Entertains the citizens of a city, making 3 unhappy citizens content. (Four after the discovery of Electricity.) However, it does not affect citizens made unhappy by military activity.
Requires knowledge of the technology Construction.
Halves all kinds of waste in a city (corruption, production waste, and food waste). In your capital, corruption and production waste is eliminated. A Granary together with a Courthouse in a city will eliminate food waste.
Also makes one unhappy citizen content (unless that citizen is unhappy about military activity), and makes the revolt cost of the city 4 times bigger.
Requires knowledge of the technology Code of Laws.
Increases the shield production in a city by 25%, or 50% with an electrical plant of any kind in the same city.
This increase in production may contribute significantly to pollution; a Factory also increases the pollution caused by the population of the city.
Requires knowledge of the technology Industrialization.
* Allows to build Hydro Plant (with Electronics and River).
* Allows to build Mfg. Plant (with Plastics).
* Allows to build Nuclear Plant (with Nuclear Power).
* Allows to build Power Plant (with Refining).
* Allows to build Solar Plant (with Environmentalism).
* Allows to build Space Component (with Superconductors, Library, University, and Research Lab).
* Allows to build Space Module (with Environmentalism, Library, University, and Research Lab).
* Allows to build Space Structural (with Space Flight, Library, University, and Research Lab).
* Allows to build Hoover Dam (with Electronics and River).
When any small city grows or shrinks, 10 food points are saved; this helps cities to grow faster and more easily withstand famine. With a Granary this is extended to cities of size 4 and above. (10 food points is half what a small city needs to grow, but more points are needed for later growth steps.)
A Granary also halves the food wasted in cities far from your capital. Together with a Courthouse it eliminates food waste.
TIP: to maximise the speed with which a city grows, you should build a Granary before it grows larger than size 4.
Requires knowledge of the technology Pottery.
Gives one extra food resource on all Ocean or Deep Ocean tiles (but not Lakes). The city needs to be coastal (next to one of these tiles) to build this improvement.
Requires knowledge of the technology Seafaring.
Requires terrain with the 'Sea' flag on the tile or an adjacent tile.
Any kind of electrical plant increases the shield production effects of any Factory or Mfg. Plant in its city by 25% each. Thus, an electrical plant in combination with either a Factory or Mfg. Plant gives a 50% production bonus over the level without any of these improvements; an electrical plant, Factory, and Mfg. Plant together give a 100% production bonus. The extra production may lead to the city generating more pollution.
However, a Hydro Plant also reduces the pollution associated with shield production to 50% of its normal value, or 25% in combination with a Recycling Center; pollution is reduced further for the player who owns the Hoover Dam. (A Hydro Plant's effect is the same as that of a Nuclear Plant; with the Hoover Dam, its effect is increased to that of a Solar Plant.)
In each city, only one Power Plant, Hydro Plant, Nuclear Plant, or Solar Plant can take effect at any one time.
Requires knowledge of the technology Electronics.
Requires Factory in the city.
Requires River on the tile or an adjacent tile.
Increases the science output in a city by 50%, or by 100% once the Great Library has been built by any player.
Requires knowledge of the technology Writing.
* Allows to build Space Component (with Superconductors, Factory, University, and Research Lab).
* Allows to build Space Module (with Environmentalism, Factory, University, and Research Lab).
* Allows to build Space Structural (with Space Flight, Factory, University, and Research Lab).
* Allows to build University (with University).
* Allows to build Great Library (with Literacy).
Increases the luxury and tax output in a city by 50%.
Requires knowledge of the technology Currency.
* Allows to build Bank (with Banking).
Reduces the pollution generated by the population in a city; this building counteracts the additional pollution associated with any two other buildings.
Requires knowledge of the technology Mass Production.
Increases the shield production in a city by an additional 25%, or 50% with an electrical plant of any kind in the same city; this effect is cumulative with that of a Factory.
With sufficient shield production, cities with a Manufacturing Plant can produce up to two units each turn (but only single units of types which cost population).
This increase in shield production may contribute significantly to pollution; a Manufacturing Plant also increases the pollution caused by the population of the city.
A Manufacturing Plant also has a small risk of suffering an industrial accident, which can lead to pollution and reduce the city's population.
Requires knowledge of the technology Plastics.
Requires Factory in the city.
Any kind of electrical plant increases the shield production effects of any Factory or Mfg. Plant in its city by 25% each. Thus, an electrical plant in combination with either a Factory or Mfg. Plant gives a 50% production bonus over the level without any of these improvements; an electrical plant, Factory, and Mfg. Plant together give a 100% production bonus. The extra production may lead to the city generating more pollution.
However, a Nuclear Plant also reduces the pollution associated with shield production to 50% of its normal value, or 25% in combination with a Recycling Center. (Its effect is the same as that of a Hydro Plant.)
A Nuclear Plant has a small risk of suffering a nuclear accident, which can lead to fallout and reduce the city's population.
In each city, only one Power Plant, Hydro Plant, Nuclear Plant, or Solar Plant can take effect at any one time.
Requires knowledge of the technology Nuclear Power.
Requires Factory in the city.
Every Ocean or Lake tile worked by the city yields one extra shield resource, as well as any Deep Ocean tile containing an oil platform. The city needs to be next to a water tile to build this improvement.
Offshore Platforms also increase the pollution caused by the population of the city.
Requires knowledge of the technology Miniaturization.
Requires Oceanic terrain on the tile or an adjacent tile.
Makes a city the capital and the center of your government. Waste in other cities (corruption, production waste, and food waste) is often related to how far away from the capital they are. On top of this, corruption and production waste in your capital itself is half of what it would otherwise be (and a Courthouse will eliminate it entirely).
The cost to enemy Diplomats and Spies of inciting a revolt in a city also depends upon the city's distance from the capital (under all forms of government). Your capital city itself cannot be incited to revolt, and enjoys a bonus when enemy agents try to evade your own agents stationed in the city, or sabotage your buildings.
Take good care of your capital, as its loss may result in your empire plunging into civil war. Losing your current palace also results in losing whatever spaceship you might have.
If the capital is in a dangerous location, or a more central capital would give a better corruption distribution, you can move your palace by rebuilding it in another city.
Under Despotism the city containing the palace gains a +75% gold bonus, and under Monarchy a +50% gold bonus.
* A 'small wonder': at most one of your cities may possess this improvement.* All players start with this improvement in their first city.
* If you lose the city containing this improvement, it will be rebuilt for free in another of your cities (if the 'savepalace' setting is enabled).
Makes a city the ecclesiastical capital, that acts as a second center of government.
Waste in other cities (corruption, production waste, and food waste) is related to how far away from the nearest capital they are. On top of this, corruption and production waste in the capital itself is half of what it would otherwise be (and a Courthouse will eliminate it entirely).
The city where this palace is located cannot be incited to revolt, and enjoys a bonus when enemy agents try to evade your own agents stationed in the city, or sabotage your buildings.
Under Despotism the city containing the palace gains a +75% gold bonus, and under Monarchy a +50% gold bonus.
Requires knowledge of the technology Theology.
* A 'small wonder': at most one of your cities may possess this improvement.
A Police Station neutralizes any unhappiness caused by one military unit in its city. It also makes up to 2 more unhappy citizens content provided they are not unhappy about aggression.
Requires knowledge of the technology Communism.
Allows a city to build veteran sea units. Also, damaged sea units which stay in town for one full turn without moving are completely restored.
Requires knowledge of the technology Amphibious Warfare.
Requires Oceanic terrain on the tile or an adjacent tile.
Any kind of electrical plant increases the shield production effects of any Factory or Mfg. Plant in its city by 25% each. Thus, an electrical plant in combination with either a Factory or Mfg. Plant gives a 50% production bonus over the level without any of these improvements; an electrical plant, Factory, and Mfg. Plant together give a 100% production bonus. The extra production may lead to the city generating more pollution.
In each city, only one Power Plant, Hydro Plant, Nuclear Plant, or Solar Plant can take effect at any one time.
Requires knowledge of the technology Refining.
Requires Factory in the city.
Building a Recycling Center reduces the amount of pollution generated by shield production in a city by 50%, or by an additional 25% in cities with another building which reduces pollution (Nuclear Plant, Hydro Plant, or Solar Plant).
Requires knowledge of the technology Recycling.
Increases the science output in a city by an additional 50%, or by 100% once the Internet wonder has been built by any player.
The total bonus is 150% if a Library, a University and a Research Lab are all present in the same city, increasing to 300% once the Great Library, Isaac Newton's College, and the Internet have all been built.
Requires knowledge of the technology Computers.
Requires University in the city.
* Allows to build Space Component (with Superconductors, Factory, Library, and University).
* Allows to build Space Module (with Environmentalism, Factory, Library, and University).
* Allows to build Space Structural (with Space Flight, Factory, Library, and University).
* Allows to build Internet (with Computers).
Doubles the intrinsic defense strength of units within a city when defending against aircraft (including helicopters).
Requires knowledge of the technology Rocketry.
Protects a city and its environs (up to 2 tiles away) from attacks by other nations' Nuclear units. A Nuclear unit not owned by you or a teammate which attacks a city with SDI Defense, or attacks a unit (or is deliberately exploded) within range, is shot down and simply has no effect. Also, doubles the intrinsic defense strength of units in the city when defending against conventional missiles.
Requires knowledge of the technology Laser.
Together with an Aqueduct, allows a city to grow larger than size 16, and further reduces the chance of a plague (by 30% of the base chance).
Requires knowledge of the technology Sanitation.
Requires a minimum city size of 9.
Any kind of electrical plant increases the shield production effects of any Factory or Mfg. Plant in its city by 25% each. Thus, an electrical plant in combination with either a Factory or Mfg. Plant gives a 50% production bonus over the level without any of these improvements; an electrical plant, Factory, and Mfg. Plant together give a 100% production bonus. The extra production may lead to the city generating more pollution.
However, a Solar Plant also reduces the pollution associated with shield production to 25% of its normal value, or eliminates it entirely in combination with a Recycling Center.
In each city, only one Power Plant, Hydro Plant, Nuclear Plant, or Solar Plant can take effect at any one time.
Requires knowledge of the technology Environmentalism.
Requires Factory in the city.
Space Components can be differentiated into Propulsion and Fuel Components. Each pair of them reduces your spaceship's travel time. You can build up to 8 pairs.
Before you can build any spaceship parts, the Apollo Program wonder must have been built by any player.
Requires knowledge of the technology Superconductors.
Requires Factory in the city.
Requires Library in the city.
Requires University in the city.
Requires Research Lab in the city.
Space Modules are the most expensive parts of spaceships. There are three different types of Space Module:
- Habitation Module: provides living space for 10,000 people.
- Life Support Module: provides food and water for the population of one Habitation Module.
- Solar Panels: provides the energy needed for any two of the other Modules.
You can build up to 4 Space Modules of each kind.
Before you can build any spaceship parts, the Apollo Program wonder must have been built by any player.
Requires knowledge of the technology Environmentalism.
Requires Factory in the city.
Requires Library in the city.
Requires University in the city.
Requires Research Lab in the city.
Space Structurals form the base of your spaceship. All other spaceship parts need to be connected to Structurals in order to function. You can build up to 32 Space Structurals.
Before you can build any spaceship parts, the Apollo Program wonder must have been built by any player.
Requires knowledge of the technology Space Flight.
Requires Factory in the city.
Requires Library in the city.
Requires University in the city.
Requires Research Lab in the city.
Increases the luxury and tax output in a city by an additional 50%, or 100% if Super Highways are also in the city. A Marketplace, Bank, and Stock Exchange together in a city yield a total bonus of 150%; adding Super Highways yields a total of 200%.
Requires knowledge of the technology Economics.
Requires Bank in the city.
* Allows to build A.Smith's Trading Co. (with Economics).
Each tile around the city with roads and without farmland, that is already generating some trade, produces one extra trade resource. The same applies to the city center tile (even if it is receiving a farmland bonus).
Also doubles the effect of any Stock Exchange in the city (increasing luxury and tax output by an additional 50%).
Super Highways also increase the pollution caused by the population of the city.
Requires knowledge of the technology Automobile.
Increases the food resources by 50% on each farmland tile which is being used around the city. Farmland tiles are those which have been irrigated a second time.
Requires knowledge of the technology Refrigeration.
Makes one unhappy citizen content. The Mysticism advance doubles this effect (except under a Communist government). With both Mysticism and the Temple of Artemis, 4 citizens are made content (3 under Communism). Does not affect citizens made unhappy by aggression.
Requires knowledge of the technology Ceremonial Burial.
* Allows to build Cathedral (with Monotheism).
* Allows to build Temple of Artemis (with Mysticism).
Increases the science output in a city by an additional 50%, or by 100% once Isaac Newton's College has been built by any player.
The total bonus is 100% if a Library and a University are present together in the same city, increasing to 200% once the Great Library and Isaac Newton's College have both been built.
Requires knowledge of the technology University.
Requires Library in the city.
* Allows to build Research Lab (with Computers).
* Allows to build Space Component (with Superconductors, Factory, Library, and Research Lab).
* Allows to build Space Module (with Environmentalism, Factory, Library, and Research Lab).
* Allows to build Space Structural (with Space Flight, Factory, Library, and Research Lab).
* Allows to build Isaac Newton's College (with Theory of Gravity).
This is not a normal improvement. Instead, setting a city's production to Coinage means its shield production is converted to tax output (money, coins!).