I cited the Berlin Wall solely as an example of a wall that mostly worked, not as an example of something we should emulate. I thought that was pretty obvious to any reader. Walls or barriers are deterrents, like the Maginot Line was a deterrent. They aren't meant to be perfect.
We have several layers of "wall" in our condo that aren't literally walls (there is one wall to the north). They are meant as deterrents, making it difficult to access the building and cause problems. I would ask Border Patrol agents what is needed in their area so they can do their job better, and listen. In some areas, we probably need nothing, or next to nothing.
