[kalos72]

But why go through all that extra effort?

Excavate an area and pile the excavated material on the inside of the "moat". Now you have a moat and wall, needing some work obviously but the vast majority of a wall system is taken care of right from the site.

Give a couple of bulldozers and some diggers a few days and I am sure they can get the basics done a couple miles a day. No?

I would prefer just chain link and elevated guard towers but that unrealistic on the scale I am looking at.