D1761/rP22984 moved siege engines from the fortress to the arsenal.
D2801/rP24470 moved champion cavalry from the fortress to the stable.
This means fortresses are less important to have. On the other hand:
D1762/rP24393 gave fortresses a territory root.
This patch does the following:
* The building time is lowered by 10%, putting it slightly below the civic centre.
* The fortress cost is changed from 1000 stone to 300 wood and 600 stone, making them more affordable (a combination of two resources is easier to achieve than a lot of one) and also improving consistency (towers cost wood too) and realism (they're not simply stone blocks).
* Compared to its parent, the fortress used to have +3 crush resistance, which is equivalent to +37% health (1/0.9^3). Because health is a lot clearer to players than resistance, this patch replaces the resistance increases with a higher health, which is rounded up a bit (6000 instead of effectively 5761).
* The increased cost and health of the Iberian are removed. There is no real historical justification for this, they look a lot weaker than e.g. Carthage's fortress, and the +50% build time could often actually be a penalty.
(Does the Iberian fortress really look 50% stronger to you?)