It feels a bit strange to search for terms like "erection" or "mating" when you're looking up reference material for spaceship construction environments, but they turn up some interesting images. And damn, the NASA Vehicle Assembly Building is mind-blowingly enormous. It looks big enough from the outside, when seen at a distance... but when the first stage of a Saturn V rocket looks relatively small within one section of the interior... holy crap, that's a big damn building.