I posted this for someone else in a help thread and I will post it here for good measure. I am showing how to edit the Eastern Culture to use the Roman walls.
This is contained within the descr_walls.txt
Ok, well first you need to find the code for the walls of the eastern faction.
I highlighted the most important part. Your going to copy egyptian and then delete it and replace it with any.
Now we go to the roman walls
this is how it will look now what you need to do is add egyptian to the culture line after the romans, and then put the any after egyptian. So it will become:
I highlighted the change. Now you will have to do this for every level of wall which is a bit time consuming but it will achieve the desired end result
Hope this helped,
~Remlap
FIXED