rope ladder
tunnel
c-4
those truly determined to get over the wall, will find a way to get over it. but it will deter a great many from even trying, and it will slow down those who make the attempt. long enough in many cases to apprehend them.
it being steel, there may be a way to electrify it in the future.
no doubt some idiots will die trying to scale the wall. get ready for the lib press to publish photos of corpses/skeletons in the desert.