selected. >> reporter: they sit like giant tombstones along the u.s. border. the president has consistently said a wall will be built. >> he say 2,000 mile a border call, you say we'll put it up when we need to? >> there's a testimonial out there for chief of former security which is general kelly, in which he said you won't see a wall from sea to shiny sea. we'll put the wall where it makes sense. >> reporter: the cost for just these test walls, $20 million, building any one of them can cost the entire 2,000 mile border could cost more than $20 billion. >> beyond there, whether the $20 billion to build the entire wall comes that's for another day? >> right now our focus is to