Don't double post like that. Edit your previous post instead.
If I were you, I would first check the cultures file. Take a look, but you won't find your answer there. What would be the next step? I guess that the looks of the wall might be tied to the techs upgrading them. Go and find these. It's probably easier to find the names of the ageup techs in the civs file, and then find them in the techtree (you will see three of them, it's up to you to think which one you need). From this point on, you should be able to continue and ""fix"" your issue.
Don't forget to backup your files if you ever want to play MP.