Legendary cities

I'm sure there are way more legendary cities then I know of but right now two are coming to mind. There is eldarado which is the legendary city of gold. And there is Atlanta which supposedly sunk. One thing that puzzles me about eldarado is that if you have lots of something it frequently loses value. There has to be a supply demand thing going. If you have a crap load of gold it wouldn't really be valualbe to you. So why hide it. Did the Gods tell you hide your crap or what? Ok there are so many Atlanta myths there is no way I can cover them. So I'm not even going to try. Maybe I'll give a go at some of them later. :) Sorry if I miss spelled stuff. I'm really bad at spelling.