When I say "next door," I'm not kidding. Launch Pad 2 is inside this building, the Spacecraft & Assemblies Transfer building. Note the black outlines around the doors, unlike the otherwise quite similar IPF building. So take another look at the SCAT and Launch Pad 1. The large "door" swung open is quite obvious on LP1. Down in the lower right is a small vertical opening. That opening docks with the tall door on the other side of the SCAT; the doors are actually the same size. Launch Pad 1's building is, er, really really really tall.