Adding to the list of things I have seen ...
The Very Large Array Telescopes in New Mexico.
The Oregon coastline from a sea plane.
The Hoover Dam. (Not to mention the entire Vegas experience!)
The St. Louis Arch.
Windsor Palace and Edinburgh Castle.
And a biggie - Mt. St. Helen's July 1980 eruption. Attending the dog races that afternoon in Portland Oregon and just sat there watching the mountain spew ash all evening!
Life is a journey - go exploring!