I can picture it in my head: A huge city with caravans going to local villages on the road that you built collecting metal from you metal mning village, a warband of your men marching through your city to check if the enemy is near your neighbouring villages, making my farms as big as i want them, villagers acting independently. ye it would be awesome but 0ad is meant to be a AOE inspired game and i remember reading the developers don't want a city builder.