It's just a gas line - there's no equipment or union there. Code allows it to be completely inaccessible. Bury it in the wall, stick it in the ground, pour a driveway over it, you're OK.
Not that I would want to do that. The skeptic in me says "some day I'll want to work on that." Especially on a building with as much 'experience' as the on in the picture!
