If you’ve ever sped through the air on a suspended monorail, chances are you were in an amusement park, taking in views festooned with rides, animals, and manicured grounds. Today, only one suspended monorail, the Wuppertal Schwebebahn in Germany, has survived since the turn of the last century—though not without incident. The suspended monorail system described by Stuart in 1925 would have run from Paris to a nearby suburb, St. Denis. “The proposed car,” Stuart wrote, would be virtually a propeller-driven airship suspended from and running along a rail. The list does not include suspended monorails, but it captures a global trend toward leveraging aerial transit in dense cities, especially those with challenging terrain, to address transportation problems.