Blackfriars Bridge in London. Not big and fancy like most of the other awesome bridges on here, but it's 145 years old and still in use today. It was recently completely removed from it's site, refurbished, and replaced back in it's place. Apparently it is the longest working iron bowstring span in North America, at 216 feet. (It's a screen grab from a video, not a video, in case you try clicking the arrow lol)