If you could recommend only one place in the whole of America...?

If a tourist was coming to the States where is the one place/area you would recommend they visit. I’m not talking whole states or even cities (although specific parts of a city are welcomed if you think they are worthy of a recommendation but please say why) I want really specific areas.

For example, I really enjoyed seeing the sailing stones in Racetrack Playa, Death Valley even though they were quite difficult to get to in our vehicle (we didn’t have a 4×4 put it that way!!!)

Ideally I want one answer and reason from each person as I am looking for things that people, if pushed, believe are the number one, must see areas of the states.

Your reasons can be anything from historic landmarks, natural beauty or even just general atmosphere. I don’t want to sway your answers by telling you the type of things I look for when visiting a place so your reasons are completely specific to you!