Here's an interesting list, the 24 UNESCO sites within the US and Puerto Rico. For a person that likes to travel, I've done a woeful job at seeing these places. My only lame excuse is that I've been saving places closer to home to visit when I 'get older'. Well guess what, I think I'm losing the race of age vs sights to see. 
https://thediscoverer.com/blog/the-24-american-unesco-heritage-sites-ranked/XvHyVpKgiwAG5at-?utm_source=blog&utm_medium=email&utm_campaign=1836629577&ST=RF_A