I have an idea about population growth, city fortifications and spatial hierachy, that I think could work with the mod. I wonder if it is possible to do within the current modding limits? Or if it would drain performance too much? What if City walls didn't automatically scale up with growing population? Basically when you build a city wall, only the current population and buildings should be housed within the city walls. So if the city is attacked, the buildings outside the wall are burned down. Population living outside the wall would either need to be crammed inside the walls or they would become refugees (migrating to adjacent tiles), or be captured by the enemy (enslaved) and so on. In order to protect more of your population/buildings you'd have to build new walls (or expand the current ones) repeatedly, but walls are expensive and require materials. And the greater population the city has, more area will have to be walled in. So the cost of walls should increase with city size (although the old stone wall could potentially be dismantled and the stones reused). Instead of expanding/replacing old walls you could allow building additional walls, resulting in outer and inner rings, protecting different structures and demographics depending on when they were constructed. It would be interesting to have the siege mechanic where you have to break through several walls to claim the city, although allowing multiple walls per city would be more complicated in keeping track of. In conjunction with this system, you could introduce a spatial hierarchy, where the Upper classes always reside in the city center and will push out the lower classes to make room, if necessary even relocate them outside the wall. Additionally, maybe lower class houses should always be built outside the walls (think slums), since that is the cheapest land to acquire and you can use the cheapest materials. Then the player would have to choose whether to build housing within the walls (upper/middle classes) or outside where they are unprotected. Another way to alter housing would be to simply reduce the choice to either build "Housing" within the walls or outside. Building within the walls would be more expensive but would bring the benefit of cramming in more people in the same area (i.e. adding floors or erecting taller houses). In this hierarchy, important buildings would always be placed within the city walls (Monuments, temples, palaces, upper class housing etc) and if you build one of those then people would be evicted/relocated to make room. If performance drain or coding isn't a problem, you could even keep track of "unused" space within the walls, building walls would leave some room for expansion and deliberate razing of buildings could likewise leave some open space.