I recall an episode of Sliders in which the gang landed on a parallel Earth where the American West was all part of the independent Republic of Texas. Though they arrived in what turned out to be a reproduction of a typical Wild West town, Rembrandt was confident they were still in San Francisco because he could see the Transamerica Pyramid in the skyline.
So there you have it - the Transamerica Pyramid, perhaps San Francisco's most well-known non-bridge structure, was not built, but made - sculpted into its present form over the long aeons by wind and water, just like Alcatraz and the Golden Gate. As a result, every parallel San Francisco will have one, except for those ones where dinosaurs still rule parts of the Earth.
I understand that when the observation deck was still open, there was a parachute up there - but only one, mind.
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