When I was in college, I got fucked in a botanical garden after hours by a security guard. Very atmospheric.
My ex also had me suck him off in the car on a long road trip, parked at in an empty church parking lot. He also tried to fuck me in a random shady bar bathroom in the French Quarter of New Orleans, but that felt a little too scary.
Parking garage bent over a car probably it for me. I wouldn’t do it now, with cameras everywhere. But was a lot of fun at the time.