Putting a swing set at the top, at least according this dubious 1930s plan.
Sure, on the one hand, adding a circus-style swing to the top of Giza's Great Pyramid would be architecturally insane and morally despicable.
But on the other hand: Wheeeeeeee!
This fluky whirligig was not drawn in fingerpaint by a four-year-old child, but actually considered by engineers from the 1930s, reports my new favoritest blog Modern Mechanix. If you can't read the balloon text, it enthuses:
Mammoth flying swings erected atop the pyramids, when Egyptian government’s consent is obtained, is amazing project planned by engineers to give tourists a thrilling bird’s eye view of the huge desert structures.
Those engineers' descendents presumably are still waiting for that consent to come through. What with the way Egypt's tourist industry has suffered with the recent revolutions, they're closer than ever to getting it. But still not quite there – despite what I'm pretty sure was Pharaoh Khufu's deathbed wish to have his tomb spinning like a carnival ride and showered with a constant rain of vomit.
Just a couple issues I'm seeing: How much ironwork would be needed to ensure those spanners don't rip chunks of stone off the 4,500-year-old monument? What would the passengers see if they're sitting on the other side of the swing coffins... er, "cars," just blue sky? When one of the vehicles breaks free and crashes nose down in the desert, would survivors get a refund? Oh, and will there be cotton candy, too?