领土可以花费
金钱通过各种基础设施升级来提高 
产出和 
幸福度，以及提高其可访问性和防御性。投资基础设施可以显著提高一个国家的收入、
人力、
研究，通常情况下，人口越多的领土中效果越显著。
建筑
在领土中可以建造各种不同的建筑可以提供各种local modifiers，比如提高人口 产出和 幸福度，调整人口中各阶级的比例，推动
同化和
改信，增加
当地人口容量, 增加区域的
要塞和
港口等。领土可建造的建筑取决于领土的级别，如 
定居点、
城市、
都会，其中一些 定居点建筑会受到领土生产的贸易品的限制。
每座建筑都有相应的 建筑成本及 
建筑时间，可由
建筑成本和
建筑时间 modifiers进行改变， 每个领土一次只能建造一座建筑，但可以排队建造多座建筑。建筑建造完成后，不需要支付任何维护费用。任何所拥有领土中的建筑都可以随时立即拆除，并将建筑成本的1/4金钱返回国库（受建造成本modifiers的影响），无论建筑是何时建成的或由谁建造的。一些事件和任务结果可能会在领土中自动建造一座建筑。
All
| Building | Province modifiers | Cost
|
Time
|
Notes | |
|---|---|---|---|---|---|
 |
Fortress |
|
150 | 720 days | Adds 1 fort level to the territory.
See |
 |
Port |
|
150 | 180 days | Can only be built on  coasts, or where ports exist at the start of the game.
Adds |
City/Metropolis only
| Building | Province modifiers | Cost
|
Time
|
Notes | |
|---|---|---|---|---|---|
 |
Aqueduct |
|
150 | 180 days |
Requires at least |
 |
Granary |
|
100 | 180 days | |
 |
Library |
|
100 | 180 days | |
 |
Marketplace |
|
100 | 180 days | |
 |
Training Camp |
|
100 | 180 days | |
 |
Tax Office |
|
100 | 180 days | |
 |
Earthworks |
|
150 | 1440 days | Limit 1 per territory. Requires the  Fortified Camps  Martial inventionRequires at least 1 fort level.
|
 |
Foundry |
|
300 | 180 days | Limit 1 per territory. Requires the Blacksmith Apprentices Martial invention.
|
 |
Great Temple |
|
300 | 360 days | Limit 1 per territory. Requires the Open Religion  Religious invention.
|
 |
Grand Theater |
|
300 | 360 days | Limit 1 per territory. Requires Gradual Economic Integration  Oratory invention.
|
 |
Academy |
|
150 | 180 days | Limit 3 per territory. |
 |
Court of Law |
|
150 | 180 days | Limit 3 per territory. |
 |
Forum |
|
150 | 180 days | Limit 3 per territory. |
 |
Mill |
|
150 | 180 days | Limit 3 per territory. |
Settlement Only
| Building | Province modifiers | Cost
|
Time
|
Notes | |
|---|---|---|---|---|---|
 |
Barracks |
|
200 | 180 days | Limit 1 per territory. |
 |
Mine |
|
200 | 730 days | Limit 1 per territory. |
 |
Tribal Settlement |
|
200 | 730 days | Limit 1 per territory. |
 |
Slave Estate |
|
200 | 730 days | Limit 1 per territory. |
 |
Farming Settlement |
|
200 | 730 days | Limit 1 per territory. |
 |
Provincial Legation |
|
200 | 180 days | Limit 1 per territory. |
Building slots
The number of buildings that can be built in any particular territory is limited by that territory's number of building slots. Each building takes up 1 slot, including those under construction, and no buildings can be built in a territory that has filled up all its slots. Territories that have more buildings than their number of permitted slots - for instance, after losing population during a sack - will lose any buildings over the limit. 
Wonders also take up a building slot, and require at least one empty building slot to begin construction.
Settlements normally only have 1 building slot (though settlement buildings are in general stronger than other buildings), which can be increased by the global settlement building slots modifier to a maximum of 2 by researching the Rural Planning 
Civic invention (though each settlement building will still have its territory cap of one). Building slots mostly become relevant when settlements are upgraded to cities, which gives a base of 2 extra building slots and an additional 1 for every 
10 pops in the city. If a city is further upgraded to a metropolis the base number of building slots is increased to 4. Other important sources of building slots in cities and metropolises, given by the local city building slots and global city building slots modifier, include:
- +1 for the
country capital - +1 for
holy sites - +1 for all cities with a tier 3 wonder with the
Engineering effect - +2 for all cities with a tier 4 wonder with the Engineering effect
- +2 for all cities with the Urban Planning Civic invention
- +1 for all cities with the
Legacy of the Builders military tradition (Levantine and Arabian traditions) - +1 for each
Make Religious Endowments religious province investment
Great wonders
- 主条目：Great wonders
Great wonders are special buildings that can be constructed in territories and give powerful bonuses to their local province or owner. Unlike standard buildings, wonders can be customized with various designs, materials, and effects, and are a significant investment that only the large and wealthy empires will be able to afford. As the centerpiece and defining feature of the local area, each territory can normally only support one great wonder, though certain wonders that are built by event can coexist with each other in the same territory. Uniquely, wonders usually give strong nation-wide effects that grow over time as the wonder's fame and prestige increases.
At the start of the game, there are a number of ancient wonders scattered all over the map, from the Temple of Jupiter Optimus Maximus in Rome to the Great Pyramids of Giza and the University of Taxila. Building additional wonders requires the Heirs of Alexander DLC.
Roads
Roads can be built by 
armies to connect two adjacent territories at the cost of gold, reducing the 
movement cost by 50% and effectively doubling the army movement speed between them, making them highly desirable for larger empires that would benefit from being able to move armies between their provinces more quickly. In addition to the army movement bonuses, connecting a territory to the road network also gives a minor boost to development, trade, and pop mobility, making them useful to build in highly populated developed territories as well as connecting frontier areas. Roads also appear graphically on the map as the network is built and extended, generally being most prominent on the terrain mapmode; if a road is built over a river, a bridge will appear. Unlike with buildings, roads are not associated with individual territories, but instead with pairs of adjacent territories (including possibly those connected over a strait); it is therefore possible (and common) for a territory to be a part of multiple different road segments. For every road connecting a territory to one of its adjacent territories, a territory will get the following stackable modifiers:
+0.001% Monthly Civilization Change- +2.5% Pop Conversion Speed
- +2.5% Pop Assimilation Speed
+2.5% Pop Promotion Speed
+1% Pop Demotion Speed
+0.05 Migration Attraction
+0.1 Pop Migration Speed
+5% Local Base Trade Routes Modifier
There are two ways to build roads - a special, cheaper method for countries with access to Italic tradition groups, and more generic one that is available to all countries. Once a road is built, it cannot be removed or destroyed, even if the territories it connects are completely depopulated.
Regular roads
Most countries need to reach at least 
Level 5 of civic advances to begin building roads.
Roads can be built using the 
Build Road unit ability toggle, which can be activated if all of the following conditions are met:
- The unit is an army
- The army has at least 10 cohorts
- The army is not in combat, moving, or exiled
- The army is in a territory that is owned by the current country, or by one of its
subjects - The army either has no commander, or its commander is loyal (i.e. has at least
34 loyalty)
Any type of army, even 
levies and 
mercenaries, can build roads, if they meet all of the requirements.
When the build road toggle is on, road construction will begin when the unit moves from one territory to another, as long as both territories either owned and controlled by the army's owner or one of their subjects, or are uncolonized (including uninhabitable territories, though not impassable terrain). When the army arrives in that other territory, if the two territories do not already have a road between them, the road will be instantly built at a base cost of 50 gold. This cost is affected by the build roads cost modifier, given only by the Civic inventions Gromatici ( -25%) and De Architectura ( -15%). If the army has at least 
1 engineer cohort, the cost of building a road is instead lowered to to 10 gold (not affected by any modifiers).
While building roads, the following modifiers are applied to the army:
−25% Morale of Armies
−70% Army movement without roads
+120% Legion maintenance cost
The toggle will be turned off if the army becomes ineligible to build roads, or if the army finishes moving to a new territory without a road on the traversed connection and the country does not have enough money to build a road.
Military roads
If a country has access to Roman traditions (in the Italic traditions group), adopting the Roman Roads tradition will give access to the special Build Military Road toggle, even if it does not currently meet the technology requirements for building roads normally. Building military roads is largely the same as building regular roads, with the main differences that the road-building army can be smaller, requiring only 5 cohorts, but must be a 
legion, and that each road costs only 25 gold per territory connection. However, note that the cost is not affected by the build roads cost modifier. As with normal road building, the cost is lowered to to 10 gold (also not affected by any modifiers) if the army has at least 1 engineer cohort.
In addition, a reduced set of modifiers is applied to the road-building army, without the increased maintenance cost or morale penalty:
- −70% Army movement without roads
Forts
- 参见：Siege
Forts can be built in territories to block the advance of enemy armies and protect important cities and strategic points from being easily captured. The size of a fort is determined by its fort level, where 1 is the minimum and 0 indicates the lack of a fort, and every 
fortress building giving 1 fort level. This means that settlements are typically restricted to a fort level of 1, while cities and metropolises are able to support larger forts. The higher the fort level, the harder it is for an enemy army to successfully take the fort.
To fully occupy a province, the attacker must besiege its 
capital and any forts in the province, after which the rest will be automatically occupied after a few days. An unprotected territory takes only 15 days to occupy, while one with a fort will take multiple months to siege down unless the attacking army launches an 
assault (usually taking heavy casualties). Each fort level gives -1 to siege progress and provides the base 
garrison of 500 per fort level, adjusted by the garrison size modifier. A besieging army needs to have at least 2000 men per each fort level to begin a siege, no matter how big the garrison is. Assaulting a fort will damage the garrison, and as soon as it reaches 0, the fort will fall. When it falls (or a new fort level is built), its garrison will start replenishing at a rate of 10% of the max garrison per month.
In addition, forts exert a zone of control (ZoC) over adjacent territories. An army that enters a hostile zone of control will not be able to progress further, and must either proceed to the fort and besiege it or return to the territory they came from. 
蛮族 ignore all zones of control and can move freely, but territories in the zone of control of a friendly fort will not lose civilization value if occupied. Friendly forts also negate 
attrition from deserts or winter, and will automatically occupy any enemy-controlled territories in its zone of control unless there is a hostile army there.
Every fort level costs a base of 0.40 gold in maintenance each month, adjusted by the 
fort maintenance modifier, except for the first capital fort.
Every province has a certain fort infrastructure capacity value, with default capacity of 5. The first fort in a territory uses up 3 points of capacity, while subsequent fort levels only use 1, and exceeding the limit gives a +25% maintenance modifier for all forts in the province by for every point over the limit. This means, with the default limit of 5, two level 1 forts in one province would use 6 points and cost [math]\displaystyle{ 0.4*1.25 = 0.5 }[/math] each per month in maintenance ( 1 in total), while a single level 2 fort costs 0.8 gold per month to maintain. Capacity can be increased through the 
Fortify Province province investment, several military traditions, some inventions, and a wonder effect.
Every territory in the province gets 
-0.25 unrest for every used fort infrastructure point, which means spreading forts out over a number of territories is much more efficient at suppressing unrest than concentrating them in a single territory, even if more expensive. As maintaining forts can be costly, it is often a good idea to remove extraneous forts that no longer serve any meaningful defensive and unrest-suppressing purpose.
Border forts
- 参见：Colonization
A country that has adopted the Castra military tradition from the Italic tribe traditions tree can have an army build a 
border fort in an owned frontier or neighbouring uncolonized territory. An army can do this action if it meets all the following conditions:
- The unit is an army
- The army has a loyal commander (defined as 34 loyalty or higher).
- The army is not in combat, moving, sieging, or exiled.
- The army has at least 5 cohorts, including at least one that is not
loyal to anyone. (This requirement implictly means that mercenaries cannot be used) - The territory the army is in:
- Doesn't already have a fortress
- Is uncolonized, or owned by the current country and borders a foreign (not uncolonized) territory
- Has a free building slot
- Borders an owned and controlled territory
- Is not next to any other owned territory with a fortress
- Doesn't already have a
When the ability is activated, the country loses 3000 manpower and builds a fortress in the territory. The country then gains ownership of the province if it was previously uncolonized, in which case the territory will also gain a 
freeman pop of the primary culture and religion. Finally, one random cohort becomes loyal to the commander, unless the general is the ruler of a non-republic, in which case the country gains 
1 tyranny instead. This ability can notably be used to colonize territories even if there is no neighbouring territory with a dominant integrated culture and state religion.
Ports
Ports are buildings that can be built in any coastal territories, as well as certain inland territories on 
major rivers (those that begin the game with a port). They allow 
ships to dock (including quickly embarking and disembarking troops), be built, repair, and supply, and are important for any nation that seeks to maintain a significant navy. The number of ports in a territory is the territory's port level, which in addition to the effects from the port buildings themselves also determines what types of ships it can build and repair: the light 
liburnians and 
triremes only require a level 1 port, the medium 
tetreres and 
hexeres require at least level 3 ports, while the very heavy 
octeres and 
mega-polyremes can only be built and repaired at ports that are at least level 5.
In addition to effects from the building itself, every coastal territory with at least one port gets the following modifiers:
+5% Supply Limit- +10% Pop Promotion Speed
For each territory in a province that has at least one port, the province also gets the following modifier:
- +2.5% Pop Migration Speed
Note that neither of these effects stack if territory has more than one port.
Pirate havens
Certain ports are home to 
pirate havens where groups of pirates are based from. These pirate havens are present in certain ports at the beginning of the game, and in addition to giving an economic boost of 
+20% Local Tax and 
+0.01% Local Population Growth to their territory they host pirate fleets, always composed of all light ships, which can rented out as naval mercenaries at times of war. When not being hired pirate fleets will eventually grow restless and go on raids, at which point the fleet while become hostile to all other navies and travel to nearby unfortified ports to plunder them, giving -25% Local Tax and +10% Demotion Speed to the plundered territories.
If pirates grow to be too much of a problem, their havens can be destroyed using the 
Root Out Pirates army ability on any controlled territory once the anti-pirate law has been passed, including those belonging to other countries that have been occupied in a 
war. This will remove the modifier (including its beneficial modifiers) and destroy the associated pirate fleet, even if it is currently out on a raid. Alternatively, pirates can be actively encouraged by passing the pro-pirate law, which will create a new pirate haven in one of the country's ports to increase its prosperity and provide more available naval mercenaries at the expense of the nearby coasts.
Destroying all ports in a pirate haven will also force any local pirate/mercenary fleets to disband, though this will not remove the pirate haven itself. If the port is ever rebuilt, the pirate fleet will eventually reappear.