In 1937, the city of San Francisco was busy preparing for the upcoming 1939 Golden Gate International Exposition when it was was approached by an engineer from Connecticut, Joseph Bazzeghin, who had an unusual proposal. He wanted to use the recently completed Golden Gate Bridge as a structure upon which to build the ultimate roller coaster, which he would call the Golden Gate Bridge Bolt. He envisioned this coaster being the centerpiece of the exposition, in the same way that the Eiffel Tower was the centerpiece of the 1900 Paris Exposition.
Image source: CA State Archives Newsletter
His plan involved attaching tracks to the cables of the bridge. These tracks would rise 300 feet above the first tower, and then drop 750 feet to the deck level of the center span — during which plunge the coaster would reach a speed of 190 mph. But then it would rise up again, 300 feet over the second tower, only to plunge 1000 feet toward the water and speed through a viaduct into Marin County.
During the second plunge riders would reach 220 mph, at which speed the force of the wind would make it impossible for them to breathe. So Bazzeghin planned to provide them with paper masks to protect their eyes, nose, and mouth.
His scheme was rejected, partially because the city was worried about drivers on the bridge being distracted by the sight of the roller coaster. But also because it would have been incredibly expensive, and possibly impossible, to build.
More info: CBS SF BayArea
, SF Chronicle