In Crusader Kings II you can construct buildings in your county capitals, and in any holdings in the county that belong to your direct vassals.
Construction is a long-time prospect, as it will take very long for most buildings to pay off. As it works on such a large timescale, quite a bit of thought should be put into what you build, where, and when.
When constructing buildings, your first priority should be your capital. The reasons for this are two-fold.
First, your capital will almost always be inherited by your heir, even if you're using Gavelkind succession. This is important, as buildings often won't pay back the investment within a single character's reign.
Second, your capital will generally have the highest tech level of your holdings, and many technologies enhance the output of your buildings, thus buildings in your capital will repay your investment faster.
Third, you should focus on your own holdings, not your vassal bishoprics and cities. Your own holdings give you their entire income, while vassals will only give you a percentage. In addition, the benefit you get from your vassals is also subject to change in the long term due to changes in opinion, while your own holdings are unaffected.
Your focus should be on improving your economic situation. The higher your income, the faster you can construct or upgrade your buildings, so while at first you'll lag behind on the military front you will quickly catch up once your economic buildings repay their cost.
After you have reached decent economic capital, with at least Castle Villages in all your holdings, you should go onto upgrading your military capabilities. At this point you should have a pretty high income, so this should be relatively quick to do. As before, concentrate on your capital holding first, then go onto other holdings.
For each military building you construct, your personal military capacity increases, and this capacity will be there for you even in times of crisis, and as such gives you a base military capacity at all times, thus vastly improving your capabilities during civil wars and also helping you in both defensive and offensive wars.
In general, you want to upgrade your holdings as fast as you can. The quicker you build the sooner your investment is repaid, and the more you can construct in the future as well.
However, you should always keep a reserve. How large this reserve should be depends on your size. Essentially you should imagine the worst possible economic scenario that could happen to your realm, and keep that much money or more in reserve at all times. As a small realm like say, Scotland, having 50 gold in reserve at all times would likely be enough most of the time, but it wouldn't be enough if you suddenly needed to hire mercenaries. As such I would recommend a reserve of 100g at the very least for any realm, as then you'll be able to recruit a band of mercenaries and pay their upkeep for almost four months through your reserve alone.
For the economical buildings, the return on investment is easily calculated.
For the castle town buildings, you get these numbers:
- Level 1, cost 100, income 1.5 - 67 years
- Level 2, cost 120, income 2.0 - 60 years
- Level 3, cost 200, income 2.5 - 80 years
- Level 4, cost 300, income 3.0 - 100 years
- Level 5, cost 400, income 3.5 - 114 years
As you can see, level 2 pays of faster than both level 1 and level 3. As such, your first goal should be level 2 in all holdings before you upgrade any further.
For the castle wall buildings, you get these numbers:
- Level 1, cost 50, income 0.2 - 250 years
- Level 2, cost 50, income 0.2 - 250 years
- Level 3, cost 100, income 0.2 - 500 years
- Level 4, cost 150, income 0.2 - 750 years
- Level 5, cost 150, income 0.5 - 300 years
On an economical level, only the first two levels will pay of during the duration of a single campaign, so any level beyond that is not worth it on just an economic level, but their other benefits do of course make them worth it.
Now, what also has to be taken into account is that for any town level after 1, you need a certain level of wall, thus giving you these numbers:
- Level 1 town, level 0 wall, cost 100, income 1.5 - 67 years
- Level 2 town, level 1 wall, cost 170, income 2.2 - 77 years
- Level 3 town, level 2 wall, cost 250, income 2.7 - 93 years
- Level 4 town, level 0 wall, cost 300, income 3.0 - 100 years
- Level 5 town, level 0 wall, cost 400, income 3.5 - 114 years
Note that the last two levels of towns do not need further wall upgrades. With wall upgrades taken into account we now get a gradual progression for how long it takes to get a return on your investment, which thus shows us that aiming for level 1 first in all your holdings, then going to the next level and so on, makes the most sense.
Due to you only getting a percentage of your vassal's income and levies, your own holdings should usually be prioritized. For castles, your own holdings are always higher priority, as they give the exact same benefits except in full. Your vassals will also improve their holdings out of their own pockets. Building all availible holdings in your provinces early will net you more "free" upgrades that way - so you might want to make maxing out the number of holdings in the counties in your demesne a priority.
While cities give higher revenue per town building than castles, you'll still get less overall due to only getting a percentage of the income.
Churches and cities however have one building each that can be useful: the monastic school and the university. The monastic school increases your tech growth in the province by 10% at level 1, and 20% at level 2, for a total of 30%, while the university increases tech growth by 20% at level 1 and 30% at level 2, but level 2 comes quite late in the game. This can make a major difference in the long run, so if you favor a tech-based approach to the game, investing in this building can be a good idea.
A Few Notes
As long as you have good stewardship, the break-even point for construction will be considerably sooner, as you get 2% more demesne income for every point of state stewardship beyond 5. Thus, at 30 state stewardship, you'll get 50% higher income, reducing the time to reach break-even by one third.
If your succession laws are gavelkind, try to keep your buildings concentrated in your capital duchy, as any other duchy could end up getting inherited by someone other than your heir. Building up a county and then losing it 20 years later due to gavelkind isn't too great an idea.
- Build in your capital first
- Don't build anything in your vassal holdings, except for monastic schools as long as you have places left to build elsewhere
- For any specific building type, get it to the same level in all your holdings before going to the next
- Prioritize economic buildings over military buildings
- Bulding all availible holdings for each province early will pay dividends late game
- Always keep a reserve of at least 100g, and preferably more
- If you're under gavelkind succession laws, keep your construction within your capital duchy as much as possible
Published by Meneth
The one exception to the 'spread everything out' rule would be your capital province. One strategy you can use to maximize your personal troops involves the "Train Troops" mission from your marshal. This mission will increase the total levies available in a single province. Thus...the larger the base levy size is, the larger the bonus is. In this case, it would make sense to focus upgrades in your capital to their maximum levels. Doing so will create the largest possible base levy size, giving the train troops mission extra power. The training ground upgrades can make these troops tougher and reinforce faster, on top of the Train Troops bonus to reinforce speed.
Just don't forget to set your marshal to train troops when war starts, and put him back on tech when it ends.