There's an outdoor bouldering wall at NCSU, which is maybe a hundred feet of ten-foot-high concrete retaining wall. Some right-thinking entity has glued holds to it: natural chunks of granite or other rocks, the largest the size of a softball planed flat to affix to the wall, the smallest a rough cube an inch or so on each side; small fragmenting bollards; and broken chips of granite countertops glued flat, with frictionless faces and edges. It starts out easy, for people who like crimpy rout...