[Endoperez]

I would use sites' effects instead of their rarity when calculating the costs. So, gem income, recruitable units/commanders, summonable units etc would increase the favorability (of building a fort in that provicne), disease, negative scales, horror attacks etc. would devrease it.

I haven't tested it, but I have a feeling the AI might start building castles into provinces it has no hope of being able to hold... So the province would HAVE to have at least one friendly neighbour, and having 2-3 would be preferred.

Also, what can FORTFUND be used for, and is the remainder in FORTFUND transferred to normal treasury whenever a castle is built?