> The other bridges discussed are iconic throughout the world.
I don't think they are. The only iconic North American bridge is the Golden Gate Bridge — this is widely recognised.
Worldwide, I'd add Tower Bridge [1], but I'm struggling to think of another bridge that is so widely known that it's instantly recognizable by a significant number of people.
Indeed, for me not being either from US or UK, Golden Gate and Tower Bridge are the only two iconic bridges I can think of. These I would recognize both by name and shape, anything else would probably be half a guess.
If shown a picture yesterday, I wouldn't have been able to name it. I think I would have known it was in New York, but when I visited it wasn't one of the sights — unlike Tower Bridge and the Golden Gate Bridge. (Perhaps I don't watch enough American TV shows; it's the kind of thing that would be in the intro-credits showing the setting is NYC.)
I think it's like the Forth Bridge near Edinburgh or Charles Bridge in Prague. They're extremely well known nationally, and may well be tourist attractions, but would most people know about them before visiting the area?