[Idea] Make the player choose which districts to wall

I am rewriting here the idea I have already written in a thread [Link], since 1M pts ideas shall be take in consideration by the devs.

Personally I don't really like the fact that walls automatically appear on the tiles adjacent to the main plaza. It is not military efficient and realistic thinking that ALL the districts of a city were surrounded by walls: in the medieval times the farms were usually left out.

I would suggest to don't even spawn cities with the basic "fence" but to add a (very cheap) "wall district" (that actually is not a district but can be placed as such on the existing ones adjacent to the main plaza or already walled districts by default, like garrisons) that would replace the Palizades, which builds walls on the districts connected to the main plaza and allowing to manage better on which districts place walls so to fortify in a more intelligent way your defenses. The other Wall infrastructures should upgrade all the wall "districts"; once you'll have built the infrastructure all the new walls that you'll build will automatically upgrade for a slightly higher production cost.

Blue: actual walls placement

Red: the districts that I would have covered with walls (more easy to defend)

PS: Wall "districts" should be placed only on tiles neighbouring a non-walled one, and don't show walls  facing an empty tile if its all surrounded by walled tiles. For QL improvements it should be possible to add to the construction tail the action to wall 2 districts if district n1 is connected to a walled district and n2 isn't but, since in the construction tail it comes after n1, and once n1's completed n2 would be bordering n1, it should still be possible to build both of them in a single turn (if there's enough Industry avaible)

PPS: also @Hensch had an idea concerning Walls (to create in game things like the Hadrian's Wall), here is the [Link] to his idea.

Note: I kindly remind you that, since 1M pts ideas shall potentially make its addition to the game, an upvote would be really appreciated.

         Thank you for your support :)