Here are some old publicity photos of Multics machines. The first one shows Betti Blank, a secretary at the Black Canyon plant, pointing at the ON switch on a 6180. This would have been taken in the mid-70s.
The second one is a promo pic of the HIS "Distributed Processing System" (distributed, apparently, throughout a very large room whose dimensions are circumscribed by cable-length limitations). This picture would have come later, since the "Level 68" marketing designation came in the late 70s.
Click either photo for a larger view.