2020. Royal Gorge Bridge, Colorado

Source:colorado.com

This bridge is one of the most extreme suspension bridges in the US, but the history behind it is even more impressive. It was built in 1929, but back then it was without the stabilizing wind cables. They were added some 50 years later, and you can only imagine what kind of a scary drive or a walk across that bridge was without these cables. Now, this marvelous engineering structure is a huge attraction, and it even has a cable car crossing for those feeling particularly brave.