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Imperator: Rome - Building Guide (for 1.2)

Written by Transatlantic Slave Trade   /   Oct 21, 2019    

This guide aims to determine what buildings are most optimal in Imperator: Rome.

Territory Types

Every territory in Imperator is one of three types. Either a settlement, city or metropolis. Settlements represent rural and undeveloped areas, while cities and metropolises represent the urban hubs of the ancient world.


  • Population Capacity: -2
  • Slaves needed for Surplus: -5
  • Population Output: -25%
  • Migration Attraction: -3
  • Migration Speed: -75%

By default, settlements aim to be 100% slaves, unless you're tribal because then it's 50% slaves 50% tribesmen. Settlements also only have 1 building slot.


  • Population Capacity: +10
  • Building Slots: +2
  • Holdings: +1

Cities aim to have a population ratio of 35% citizens, 35% freemen, and 30% slaves (Tribes like to squeeze in 4% tribesmen). Cities gain an additional building slot for every 10 pops in the city.

Metropolis Requires 80 pops to build

  • Population Capacity: +15 & +25%
  • Building Slots: +4
  • Local Import Routes: +1
  • Holdings +2
  • Promotion Speed: +10%
  • Migration Attraction: +2

Metropolises are basically a buffed up city. Mechanically they are identical.

Settlement Buildings

Settlements can only ever have one building in them at a time. If you want to change it, then you'll have to delete the old one. This includes forts.


  • Base Cost: 50
  • Increases the fort level by 1

Forts aren't super useful in settlements because the building slot cap means you can only build level 1 forts in them without upgrading the territory into a city.


  • Base Cost: 120
  • Local Manpower: +20%
  • Local Freeman Happiness: +20%
  • Local Freeman Ideal Fraction: +15%

Barracks basically change the territory from a tax producing slave province into a manpower producing freeman province. Settlements with a barracks in them will default to 75% freemen and 25% slaves. All the slaves in the territory will quickly promote into freeman, while tribesmen will promote much more slowly. Useful only if you have chronic manpower problems and money to spare.

Slave Estate

  • Base Cost: 120
  • Population Capacity: +25%
  • Local Monthly Food Modifier: +50%
  • Local Slave Output: +40%

Build this if you want to turn the territory into a money producing machine. Pretty much the go to building if you want tax instead of commerce income, aka every province outside of the capital. The population capacity boost means more people will migrate to the territory which is a nice bonus.


  • Base Cost: 120
  • Population Capacity: +25%
  • Slaves needed for surplus: -5

This is Imperators version of a manufactory from EU4. With this you only need 10 slaves instead of 15 to produce a surplus of goods in the territory. Needless to say these can only be built in mineral related tradegood provinces, such as stone, iron and marble. Build these if you're looking for surplus' and food isn't an issue.

Farming Settlement

  • Base Cost: 120
  • Population Capacity: +25%
  • Slaves needed for surplus: -5
  • Local Monthly Food Modifier: +50%

Same as the mine but for food producing provinces instead. Use if you want to produce surplus amounts of food goods for commerce income. Particularly useful in cold or desert provinces where food receives a -40% production modifier.

Tribal Settlement

  • Base Cost: 120
  • Population Capacity: +25%
  • Local Tribesmen Output: +40%
  • Local Tribesmen Happiness: +20%

Tribal countries love these, as their default pop ratio in settlements is 50% tribesmen and 50% slaves. Good to ensure a steady stream of manpower and tax money in tribal provinces. Not so useful for civilised countries as tribesmen will always demote into slaves or other pops.

Provincial Legation

  • Migration Speed: +75%
  • Assimilation Speed: +0.2

Basically negates the debuff that settlements get for migration. Build a couple of these then turn on Centralise Population and sit back and watch as the people flock into the cities. The assimilation buff is kind of weak. You're better off using cities and governor policies to assimilate the population instead. (For reference, cities can build theatres which increase assimilation by 1.0 instead of 0.2. A governor with 10 finesse can assimilate at a speed of 5.5 with the policy)

City / Metropolis Buildings

Cities are the backbone of a civilised society. What's more is that they're great to specialise with.

Training Camp

  • Base Cost: 50
  • Local Manpower: +10%

Pretty straight forward. Gives a buff to the manpower production of the city. In my experience it's better just to build Forums, which increase the number of freemen in the city instead. Use if your freemen have 100% happiness already.


  • Base Cost: 50
  • Fort Level: +1

With enough building slots you can turn a city into an unsiegable super fortress. At which point the AI will probably just go around your city. Having level 1 forts in your major cities are good though, as they prevent the city from getting sacked and turned into slaves easily.


  • Base Cost: 50
  • Ship Recruit Speed: +10%
  • Cohort Recruit Speed: +10%
  • Starting Experience: +5%

Very useful for building ships, especially bigger ships. Also useful for replacing war elephant stacks. Can be stacked to produce highly trained units at ludicrous speeds. I'd only build these in scenarios where you're likely to lose lots of troops and have to replace them quickly, such as in multiplayer games.


  • Base Cost: 50
  • Commerce Value: +25%

Increases commerce income in the territory. Pretty straight forward. Only build if the income you'll gain from it is above 0.08, as at that point it will take 50 years to pay itself off. Remember to give out holdings to people in your country (or yourself) as that increases commerce income.

Tax Office

  • Base Cost: 50
  • Local Tax: +10%

Same as the marketplace but for tax. Only build if the income you'll gain from it is above 0.08, as at that point it will take 50 years to pay itself off. Stack with Mills for big bucks.

Court of Law

  • Base Cost: 50
  • Territory impact on provincial loyalty: +0.02

Basically the equivalent for -2 unrest. Useful for chronically disloyal provinces, like with the Seleucids. Wouldn't bother building these in mildly disloyal provinces.


  • Base Cost: 50
  • Research Points: +2.5%
  • Promotion Speed: +0.5

Good to mix with Libraries. Use these if your citizen happiness is already 100% in the province. Promotion speed is a nice for promoting Tribesmen into Citizens or Freemen, as they promote at a speed of 0.4


  • Base Cost: 50
  • Provincial Food Capacity: +200

Useful to prevent your population from starving to death during sieges. Which is only a really problem for isolated city states. Would pretty much never recommend these otherwise.


  • Base Cost: 50
  • Local Citizen Happiness: +3%
  • Local Citizen Ideal Fraction: +6%

The go to building for turning your city into a research producing machine. Build these if you want to get ahead in technology. Once your citizens have 100% happiness, build Academies instead. Increases the ratio of citizens in the city.


  • Base Cost: 50
  • Local Freemen Happiness: +3%
  • Local Freemen Ideal Fraction: +6%

The manpower equivalent of the Library. Build these if you want to turn a city into a manpower producing hub. Once your freemen have 100% happiness, build training camps instead. Increases the ratio of freemen in the city.


  • Base Cost: 50
  • Local Slave Output: +3%
  • Local Slave Happiness: +3%
  • Local Slave Ideal Fraction: +6%

Increases the ratio of slaves in the city and buffs their output by 6%. Build these to build tax havens. Once their happiness is 100% build Tax Offices instead.


  • Base Cost: 50
  • State Religion Happiness: +3%
  • Conversion Speed: +1.0

Great for showing savage minds the truth. Most pops convert at a speed of 0.8 and tribesmen at 0.4, so this will basically supercharge that speed. As an added bonus, all pops of your religion will basically get a 3% output bonus. So still useful even if there are no pops left to convert.


  • Base Cost: 50
  • Primary Culture Happiness: +3%
  • Assimilation Speed: +1.0

Great for flipping savages to your culture. Pops will assimilate especially slower if they're not your religion, so focus on Temples first. As an added bonus, pops of your primary culture will get the equivalent of a 3% output bonus. So still useful even if there's nobody left to assimilate.


  • Base Cost: 50
  • Population Capacity: +4

I always build these in my capital city to get that much desired metropolis. Increases the base population capacity of the city, which scales with all the other factors that affect population cap, so this tends to actually be a bonus of 6-10 depending. The metropolis buffs will also apply to your Aqueducts, providing an extra +25% pop cap per Aqueduct. The nice thing about having a lot of pops in your capital city is that they all receive a +75% output buff, making it more efficient to have people there than anywhere else.

Final Notes

I'd recommend you build at least one city in every province to help culture flip it over to yours. The AI will eventually turn it from slaves and tribesmen into something nice and useful.