The title says it... In my campaing i usually build forts near every mountain pass, or every river to keep the enemies out... And i have no need to pay for them... I just build them whenever i want, as many times that i want... IMHO if the forts costed some money, it would add to the strategic part of the game (playing as Pontos you would need to carefully consider where and how to build your forts, in one campaign i had like 8 forts holding down the seleucids, giving a few years to prepare before they could attack me)
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