It seems like with a few notable exceptions, the achievement does not get rewarded properly. Hitting structures such as barricades, gates, the center trebuchet/catapult, & tents with your weapon skills (i.e. Fire Storm + autos) does not get credit. (Confirmed with dealing up to 50% a wayward structure's HP with one other player helping. Not confirmed for center siege weapons since that isn't out of the way for testing.)Hitting the above mentioned structures with player-deployed siege weapons does not give credit toward achievement (see exception below)Exceptions:(1) Pillage the Lighthouse rewards hitting all structures with your weapon skills properly. It seems like some of these structures do not have the blue buff that other structures normally have.(2) Using Flaming Rams to open the initial gate of the all areas seems to give 1 structure credit consistently if you get at least one flaming ram auto off once (hence why the gates are always flooded with like 20 flaming rams.)