In Crusader Kings 3, you can upgrade your duchies by building structures there. These special buildings give the Duchy a massive bonus, allowing you to enhance your land. However, these bonuses are often overlooked because of the cost. So, here's a complete guide on what Duchy buildings are in CK3, and which ones you should build for your realm.
This guide is current to the Update 1.13.0.4!
What are Duchy Buildings in Crusader Kings 3?
Duchy buildings are special buildings in CK3 that provide strong perks and benefits, ranging from increased taxes to even greater military power. These buildings can only be constructed by Feudal, Clan, or Administrative rulers in the De Jure capital of a Duchy and are accessible only if you hold the Duchy title. You also need to right Cultural Innovations unlocked to construct these buildings.
Each Duchy can support only one Duchy building, and these buildings have three levels, each more expensive and beneficial than the last. The cost of these buildings starts at 600 and can increase by an additional 300 gold every level and it takes 5 years to construct or upgrade. This cost is subject to change and depends on your character's traits and stats. Each Duchy’s count capital has an extra building slot for Duchy buildings.
List of all Duchy Buildings in Crusader Kings 3
Here's the complete list of every special Duchy building with their type in Crusader Kings 3, and why you should build them in your realm:
| Duchy Building | Type | Reason |
|---|---|---|
| Crown Smithies | Military | If you've got an infantry-heavy army, Crown Smithies can be a great choice. They also provide -10% to your army's maintenance and boost the rarity of any commissioned artifacts. |
| Archery Grounds | Military | Similar to Crown Smithies, but with archers instead of infantry. This includes both regular archers and even archer cavalry. You also get a 10% reduction in army maintenance. |
| Jousting Grounds | Military | If you like using Calavry or War Elephants, then having a Jousting Ground can be quite strong for your stationed Men-At-Arms. Moreover, you also get a 10% reduction in army maintenance. |
| Leisure Palaces | Economy | Provides strong boosts to Duchy control and Intrigue Schemes. If you have lower control over a realm or lack Intrigue, this building can be quite strong to make up for that. |
| Marches | Military | This building is a defensive stronghold and helps you create an impenetrable border. Great to build near hostile regions. Moreover, you get a +30% Holding Tax, which provides a good boost. |
| Military Academies | Military | Provides a significant -30% reduction in army maintenance, lets you train knights, and create +3 Men-At-Arms regiments. A must-have for almost any playthrough. |
| Royal Armories | Military | Provides you with an additional 40% Levy Size and reduced army maintenance cost, making it great for aggressive playthroughs. Also provides a 30% boost to any stationed Men-At-Arms. |
| Royal Reserves | Economy | Increases your Popular Opinion and provides a +30% boost to the Duchy's development. Provides a flat increase to your monthly income of up to 1.4 Gold. Great choice for an early game. |
| Siege Works | Military | If you want a strong siege regiment, then you need one of these buildings in your realm. No benefit to other Men-At-Arms. |
| Tax Offices | Economy | Provides a massive +20% boost to Holding Taxes for your entire Duchy. Must-have if you are having a gold shortage. |
| Royal Gardens | Economy | Increases your popular opinion, increases your Prestige gain, and adds a 1.4 Gold increase to Holding Taxes. Worse version for Royal Reserves. |
| Burial Site(Requires Legends of the Dead DLC) | Economy | Significantly increases Control Growth and Plague Resistance in your Duchy. Also provides +1 monthly Piety and increased Legitimacy gain. Great overall option. |
Best Duchy Buildings to Build for Early Game
Leisure Palaces are a fantastic early game choice because of their Realm and Duchy modifiers. The bonus to prestige is incredibly good, and because of the sheer amount of stress in the early game, any way to reduce it quicker is better.
What’s more, the Leisure Palaces improve scheme's success chance, making them perfect if you’re planning for lots of intrigue and assassinations.
Best Duchy Building to Build for Warfare
Military Academies are the best Duchy Building if you’re map painting/conquering a lot. This is because it increases the number of Knights you can wield, making early battles much easier. It also reduces by 30% Army Maintenance, meaning you’ll not go bankrupt waging war early.
Best Duchy Building to Build for Economy
If you're running short on gold, or have a huge standing army, then building economy Duchy buildings is your best bet. I prefer building Tax Offices as they provide a solid 20% increase in Holding Taxes from all the counties under the Duchy. You should try to build these in Duchies with high overall Development. I pair them with other economy buildings like Manor Houses to maximize the effect of the special building.
Best overall Duchy Building
Marches are the best overall Duchy Building at any point in the game. The sheer range of bonuses make them perfect for your most favorable Duchies. A defensive and offensive choice, getting a bonus to supply limit, levy reinforcement rate, and garrison size is huge. And the slow down in raid speed makes it perfect to allow you to react to any hostile invasion.
For more on Crusader Kings 3, check out What is Cultural Acceptance in Crusader Kings 3: Royal Court and how to increase it on Pro Game Guides.
