I used to build my wall before the water ditch. Then my wall was rammed to zero multiple times, but the water ditch wasn't affected. Does any have stats on when to build one vs. the other?
If you're dominant or the attacker is a ramless noob, the city wall shines at its best. The reason behind this is the way attacks work. Basically you have a simulated combat before the real combat, in which the city wall is damaged or destroyed and the real combat will be calculated based on the wall's intermediate level. (After the real combat, the city wall is damaged again and only the final value is shown in the report.) If the attacker has enough rams (or enough off with a noobish amount of rams), the ram is destroyed in the intermediate calculation, rendering it useless for the combat itself. Similarly (obviously), if the first attack destroys it, it's useless for the following levels. If you're defending your capital, you have the stonemason's lodge to additionally support your city wall, making it harder to destroy aswell in the intermediate calculation aswell as the final calculation. Soooo, I'd say it depends on the situation and on the attacker. I made the experience, that roman's city wall especially is often kinda useless when battling versus hammers with enough rams, but I also made the experience, that many off players are noobs, which build way too few rams. xD
All said by Be2-e4 but I would like to add some of my gamestyle to your question:
Walls can be built in any village, it is very good for breaking enemy raids.
But I do not recomend building wall level for Governors. Only Dukes and Kings should make walls.
Governor will profit more overtime by building ress fields or troops for raids then raising defense, sicne governor does not require defense since it is not attacked by enemy dukes or kings.
Catapults are too expensive and more important TOO SLOW to destroy more then you can build if you are active.
Specially if you gold but even without gold, it is better to raise resource fields in start and get it smashed later then to raise walls first, loose ress production overtime and so on.
Ditch is a must have for a Treasury or Off City. Because mostly those type of "real estates" gets catapulted.
Building defensive structures in support village is bad math.