Castles are holdings held primarily by feudal lords. They pay lower taxes than cities and temples, but provide better levies, both in quality and quantity. Castles are the county seat (capital) for most counties; as such, their higher fort level as compared to temples and cities helps the county to better withstand sieges and raids.
Characters of the following government types can hold castles without penalty: feudal, iqta, monastic feudal, merchant republic, Confucian bureaucracy and Chinese imperial.
Castles are composed of buildings which must be upgraded to increase fort level, levies, or income. In addition to the buildings below, castles are allowed to build culture-specific buildings depending upon the culture of the holding's owner. Note that castles are the only source of cavalry levies, and the only holding type where cultural buildings and training grounds can be built.
Constructing a castle (or city) can prevent a formerly-normadic province from reverting due to nomad agitation.
Hindu characters must be of the 
caste before they can be granted castles.
Note that the effects of building upgrades stack.
Base Stats
All holdings have certain base statistics, providing income, fort level, and levies, so even a newly constructed holding will have some value.
| Characteristic | Value | |
|---|---|---|
|
Income | 4 |
|
Fort level | 3 |
|
Levies | 60 light infantry 150 heavy infantry 15 light cavalry |
Castle Fortifications
These buildings increase fort level, increasing the time it takes an attacking army to siege the holding and reducing the amount of free loot available to raiders.
| Name | Price | Build time | Effects | Requirements | Tech Requirements |
|---|---|---|---|---|---|
| Castle Fortifications I | 50 gold | 182 days | +0.5 fort level | ||
| Castle Fortifications II | 50 gold | 182 days | +0.5 fort level | Castle Walls I Castle Fortifications I |
Improved Keeps 1 |
| Castle Fortifications III | 50 gold | 182 days | +0.5 fort level | Castle Fortifications II | Improved Keeps III |
| Castle Fortifications IV | 100 gold | 365 days | +1 fort level | Castle Fortifications III | Improved Keeps V |
| Castle Fortifications V | 100 gold | 365 days | +1 fort level | Castle Fortifications IV | Improved Keeps VII |
Walls
Walls increase levy size and fort level, raising the defensive capacity. They also slightly increase yearly income from the holding.
| Walls | Price | Build time | Effects | Requirements | Tech Requirements |
|---|---|---|---|---|---|
| Castle Walls I | 50 gold | 365 days | +0.5 fort level +2.5% levy size +0.2 income |
||
| Castle Walls II | 50 gold | 547 days | +0.5 fort level +2.5% levy size +0.2 income |
Castle Walls I | Improved Keeps I |
| Castle Walls III | 100 gold | 730 days | +1 fort level +5% levy size +0.2 income |
Castle Walls II | Improved Keeps IV |
| Castle Walls IV | 150 gold | 1095 days | +1 fort level +5% levy size +0.2 income |
Castle Walls III | Improved Keeps VI |
| Castle Walls V | 150 gold | 1460 days | +1.5 fort level +10% levy size +0.5 income |
Castle Walls IV | Improved Keeps VIII |
| Theodosian Walls | 150 gold | 1460 days | +4 fort level | Castle Walls V, Constantinople |
Keeps
Keeps are arguably the most important building for castles. They increase garrison size, thereby increasing the defensive capacity of the holding, and increase levies, giving the holder the ability to field more troops.
| Name | Price | Build time | Effects | Requirements | Tech Requirements |
|---|---|---|---|---|---|
| Keep I | 150 gold | 547 days | +5% levy size +5% garrison size |
||
| Keep II | 200 gold | 730 days | +10% levy size +10% garrison size |
Castle Walls I Keep I |
|
| Keep III | 300 gold | 1095 days | +15% levy size +15% garrison size |
Castle Walls II Keep II |
Improved Keeps II |
| Keep IV | 400 gold | 1460 days | +20% levy size +20% garrison size |
Keep III | Improved Keeps IV |
| Keep V | 500 gold | 2190 days | +25% levy size +20% garrison size |
Keep IV | Improved Keeps VI |
| Keep VI | 500 gold | 2190 days | +30% levy size +20% garrison size |
Keep V | Improved Keeps VIII |
Militia Training Grounds
Militia training grounds increase the output of light infantry and archers in a holding. Both are low quality troops, but tend to make up the majority of armies, being very numerous, and are two of the best troop types during the skirmish phase at the start of a battle.
| Name | Price | Build time | Effects | Requirements | Tech Requirements |
|---|---|---|---|---|---|
| Militia Training Ground I | 100 gold | 365 days | +80 light infantry +10 archers |
||
| Militia Training Ground II | 120 gold | 547 days | +50 light infantry +50 archers |
Castle Walls I Militia Training Ground I |
Castle Infrastructure I |
| Militia Training Ground III | 200 gold | 1095 days | +20 light infantry +90 archers |
Militia Training Ground II | Castle Infrastructure V |
| Militia Training Ground IV | 300 gold | 1095 days | +30 light infantry +120 archers |
Militia Training Ground III | Castle Infrastructure VII |
Training Grounds
Training grounds are one of the key buildings that make castles the best holding for levies. This upgrade gives increased morale to all levies raised from the holding, which can make the difference between routing the enemy and being routed. Additionally, the increased levy reinforcement rate means that losses will be replenished faster, and is key when fighting a defensive war. This building is also useful if you intend to form your own mercenary band.
| Name | Price | Build time | Effects | Requirements | Tech Requirements |
|---|---|---|---|---|---|
| Training Grounds I | 200 gold | 730 days | +10% morale +10% levy reinforcement rate +20 retinue size |
Castle Walls II | |
| Training Grounds II | 250 gold | 1095 days | +15% morale +15% levy reinforcement rate +20 retinue size |
Training Grounds I | Castle Infrastructure III |
| Training Grounds III | 300 gold | 2190 days | +20% morale +20% levy reinforcement rate +20 retinue size |
Training Grounds II | Castle Infrastructure VI |
Barracks
Barracks provide castles with heavy infantry and pikemen, which gives an army staying power and the ability to kill in the melee phase of combat.
| Name | Price | Build time | Effects | Requirements | Tech Requirements |
|---|---|---|---|---|---|
| Barracks I | 100 gold | 365 days | +30 heavy infantry +15 pikemen |
||
| Barracks II | 120 gold | 547 days | +40 heavy infantry +15 pikemen |
Castle Walls I Barracks I |
|
| Barracks III | 200 gold | 730 days | +45 heavy infantry +20 pikemen |
Castle Walls II Barracks II |
Castle Infrastructure I |
| Barracks IV | 300 gold | 1095 days | +50 heavy infantry +25 pikemen |
Barracks III | Castle Infrastructure III |
| Barracks V | 400 gold | 2190 days | +60 heavy infantry +25 pikemen |
Barracks IV | Castle Infrastructure V |
| Barracks VI | 500 gold | 2190 days | +65 heavy infantry +30 pikemen |
Barracks V | Castle Infrastructure VII |
Stables
Stables are another key to the power of castles. They are the only way outside of culture specific buildings to acquire heavy cavalry (the best troop type in the game) and provide lots of light cavalry, which is an all around useful troop type, and great for chasing down fleeing armies.
| Name | Price | Build time | Effects | Requirements | Tech Requirements |
|---|---|---|---|---|---|
| Stables I | 100 gold | 365 days | +35 light cavalry | ||
| Stables II | 120 gold | 547 days | +45 light cavalry | Stables I Castle Walls I |
|
| Stables III | 200 gold | 730 days | +55 light cavalry | Stables II Castle Walls II |
Castle Infrastructure II |
| Stables IV | 300 gold | 1095 days | +55 light cavalry +5 heavy cavalry |
Stables III | Castle Infrastructure IV |
| Stables V | 400 gold | 2190 days | +55 light cavalry +10 heavy cavalry |
Stables IV | Castle Infrastructure VI |
| Stables VI | 500 gold | 2190 days | +55 light cavalry +20 heavy cavalry |
Stables V | Castle Infrastructure VIII |
Castle Towns
Castle towns are the economic upgrade for castles, and are thus extremely important.
| Name | Price | Build time | Effects | Requirements | Tech Requirements |
|---|---|---|---|---|---|
| Castle Town I | 100 Gold | 365 Days | +2 income | ||
| Castle Town II | 120 Gold | 547 days | +2 income | Castle Town I Castle Walls I |
|
| Castle Town III | 200 gold | 730 days | +2 income | Castle Town II Castle Walls II |
Castle Infrastructure II |
| Castle Town IV | 300 gold | 1095 days | +2 income | Castle Town III | Castle Infrastructure IV |
| Castle Town V | 400 gold | 2190 days | +2 income | Castle Town IV | Castle Infrastructure VI |
| Castle Town VI | 500 gold | 2190 days | +2 income | Castle Town V | Castle Infrastructure VIII |
Shipyards
Castle shipyards are buildings that can only be built in coastal provinces; they provide ships that can be used to transport troops.
| Price (gold) | Build time (days) | Effects | Requirements | Tech Requirements | Notes | |
|---|---|---|---|---|---|---|
| Castle Shipyard I | 100 | 365 | +4 galleys | Shipbuilding I | Only available in coastal holdings | |
| Castle Shipyard II | 100 | 730 | +5 galleys | Castle Shipyard I | Shipbuilding II | Only available in coastal holdings |
| Castle Shipyard III | 100 | 1095 | +6 galleys | Castle Shipyard II | Shipbuilding III | Only available in coastal holdings |
| Castle Shipyard IV | 100 | 1460 | +7 galleys | Castle Shipyard III | Shipbuilding IV | Only available in coastal holdings |
Cultural Buildings
Cultural Buildings and Steppe Cultural Buildings can be built in castles, varying in name and specific contributions to their levy on the culture of the province the castle holding is in.
Beyond contributing levy forces, many cultural buildings also give a bonus to the offence, defence, or morale levels of specific units. As these bonuses apply to the retinue of that character if these cultural buildings are built in the capital castle holding, placement of the capital can impact the quality of the army.
All Cultural Buildings, except for the Steppe Cultural Buildings, have the same requirements.
| Price (gold) | Build time (days) | Requirements | Tech Requirements | Notes | |
|---|---|---|---|---|---|
| Cultural Building I | 200 | 730 | Castle Walls II | Improved Keeps II | Benefits will vary depending on the culture of the province |
| Cultural Building II | 300 | 1095 | Cultural Building I | Castle Infrastructure I | Benefits will vary depending on the culture of the province |
| Cultural Building III | 400 | 2190 | Cultural Building II | Castle Infrastructure II | Benefits will vary depending on the culture of the province |
| Cultural Building IV | 500 | 2190 | Cultural Building III | Castle Infrastructure IV | Benefits will vary depending on the culture of the province |
Steppe Cultural Buildings exist for certain (steppe) cultures when building in steppe terrain, instead of the default Cultural Buildings.
| Price (gold) | Build time (days) | Effects | Requirements | Tech Requirements | |
|---|---|---|---|---|---|
| Steppe Barracks I | 100 | 365 | +25 Heavy Infantry +20 Light Cavalry |
||
| Steppe Barracks II | 120 | 547 | +35 Heavy Infantry +20 Light Cavalry |
Steppe Barracks I | Castle Walls I |
| Steppe Barracks III | 200 | 730 | +40 Heavy Infantry +25 Light Cavalry |
Steppe Barracks II | Castle Walls II Improved Keeps II |
| Steppe Barracks IV | 300 | 1095 | +45 Heavy Infantry +30 Light Cavalry |
Steppe Barracks III | Castle Infrastructure I |
| Steppe Barracks V | 400 | 2190 | +55 Heavy Infantry +30 Light Cavalry |
Steppe Barracks IV | Castle Infrastructure III |
| Steppe Barracks VI | 500 | 2190 | +60 Heavy Infantry +35 Light Cavalry |
Steppe Barracks V | Castle Infrastructure V |
| Steppe Stable I | 100 | 365 | +10 Horse Archers +25 Light Cavalry |
||
| Steppe Stable II | 120 | 547 | +20 Horse Archers +25 Light Cavalry |
Steppe Stable I | Castle Walls I |
| Steppe Barracks III | 200 | 730 | +20 Horse Archers +35 Light Cavalry |
Steppe Stable II | Castle Walls II Improved Keeps II Castle Infrastructure II |
| Steppe Barracks IV | 300 | 1095 | +20 Horse Archers +35 Light Cavalry +5 Knights |
Steppe Barracks III | Castle Infrastructure IV |
| Steppe Barracks V | 400 | 2190 | +20 Horse Archers +35 Light Cavalry +10 Knights |
Steppe Barracks IV | Castle Infrastructure VI |
| Steppe Barracks VI | 500 | 2190 | +20 Horse Archers +35 Light Cavalry +20 Knights |
Steppe Barracks V | Castle Infrastructure VIII |
Gompa Monasteries
Fortified gompas protect the monasteries and universities that lie within them. Can only be built by Monastic Feudal rulers.
| Name | Price | Build time | Effects | Requirements | Tech Requirements |
|---|---|---|---|---|---|
| Gompa Monastery I | 150 gold | 547 days | +5% levy size +5% garrison size +2.5% tech spread rate +0.01 cultural tech points +0.05 liege piety |
||
| Gompa Monastery II | 200 gold | 730 days | +5% levy size +5% garrison size +5% tech spread rate +0.02 cultural tech points +0.05 liege piety |
Gompa Monastery I Castle Walls I |
|
| Gompa Monastery III | 300 gold | 1095 days | +5% levy size +5% garrison size +7.5% tech spread rate +0.03 cultural tech points +0.05 liege piety |
Gompa Monastery II | Church Infrastructure II |
| Gompa Monastery IV | 400 gold | 1460 days | +5% levy size +5% garrison size +10% tech spread rate +0.04 cultural tech points +0.05 liege piety |
Gompa Monastery III | Church Infrastructure IV |
Special Fortifications
This building chain is accessible when the owner or any liege of the castle has the Castellan or Peaceful-Castellan bloodlines. See Bloodline#Forged_Bloodlines
| Name | Price | Build time | Effects | Requirements | Tech Requirements | Notes |
|---|---|---|---|---|---|---|
| Insulated Sections | 125 gold | 365 days | +0.5 fort level +5% morale |
Requires an owner or any liege with the Castellan or Peaceful-Castellan bloodlines. | ||
| Killing Fields | 250 gold | 560 days | +1 fort level +5% morale +5% garrison size |
Insulated Sections | Improved Keeps III | Requires an owner or any liege with the Castellan or Peaceful-Castellan bloodlines. |
| Extended Machicolations | 450 gold | 760 days | +1.5 fort level +15% garrison size +50 archers |
Killing Fields | Improved Keeps V | Requires an owner or any liege with the Castellan or Peaceful-Castellan bloodlines. |
| Reinforced Barbican | 750 gold | 1250 days | +2 fort level +20% levy size +30% garrison size +100 light infantry |
Extended Machicolations | Improved Keeps VII | Requires an owner or any liege with the Castellan or Peaceful-Castellan bloodlines. |
Oppressive Fortifications
This building chain is accessible when the owner or any liege of the castle has the Murder-Builder bloodline. See Bloodline#Forged_Bloodlines
| Name | Price | Build time | Effects | Requirements | Tech Requirements | Notes |
|---|---|---|---|---|---|---|
| Gloomy Monument | 125 gold | 365 days | -5% local revolt risk +.05 liege prestige |
Castle Infrastructure II | Requires an owner or any liege with the Murder-Builder bloodline. | |
| Connected Watchtowers | 250 gold | 560 days | +1 fort level -5% local revolt risk +5% garrison size |
Gloomy Monument | Castle Infrastructure IV | Requires an owner or any liege with the Murder-Builder bloodline. |
| Lonely Spire | 300 gold | 560 days | +1 fort level -5% local revolt risk +5% garrison size |
Connected Watchtowers | Castle Infrastructure VI | Requires an owner or any liege with the Murder-Builder bloodline. |
| Palace of Justice | 450 gold | 760 days | +1 fort level -5% local revolt risk +5% garrison size |
Lonely Spire | Castle Infrastructure VIII | Requires an owner or any liege with the Murder-Builder bloodline. |