Airliner Number 4: The 9 Deck Plane Concept From The 1920s

When Boeing rolled out the mighty 747 in 1969, the world was mesmerized by the idea of a twin-decker airplane. Though a partial upper deck, the ability to design, build, and roll-out a multi-deck aircraft was new. Three decades later, when Airbus introduced the A380, a true double-decker, it was once again a new thing in the world of commercial aviation.