Europe Walls "1x4"

In for example Europe and other maps like it you can build walls.
I just wonder how you can build the wall cause if you look at the farm it takes
"2x2 green spots" I think, and the walls in Europe takes 1x4, how do i make it so?

change the pathing map in unit editor
you can see the pathing by going into view - view pathing ground or something like that.

well then how do i make it 1x4?

Use the pathing map of one of the existing wall destructibles.