The B-36 Peacemaker had catwalks built into the wings so that crew could work on the engines in flight!
Bonus fact: the engines were mounted as pushers to reduce drag so that it could fly from Pittsburgh to Moscow without refueling, 10,000 miles!
The B-36 is the largest mass-produced piston-engined aircraft ever built. It had the longest wingspan of any combat aircraft ever built, at 230 ft (70 m).
The B-36 was the primary bomber, capable of nuclear delivery, of Strategic Air Command (SAC) until it was replaced by the jet-powered Boeing B-52 Stratofortress.
Many people see the B-52 and think it is the biggest bomber in the Air Force. In reality, the B-36 was larger. The Peacemaker had a wingspan of 230 ft and a length of 162 ft. Compared to the B-52's 185 ft wingspan and 159 ft length, the B-36 dwarfed its replacement.
Evening at Blackfeet camp. Montana. Early 1900s. Glass lantern slide by Walter McClintock. Source - Yale Collection of Western Americana, Beinecke Rare Book and Manuscript Library
There, I put the door stop in place.