Somewhere I have a docu on it — the sculptor first pitched the idea of the Confed monument at Stone Mountain, joined the Klan, the whole works; he got pissed off about something, quit the Klan, and conceived the Rushmore project. He wanted a museum about the US in that Hall of Records, and including a copy of the Declaration of the Independence, or the Constitution, or both, I forget. Fascinating guy. One of his rock cutters branched out and started that unfinished Crazy Horse monument.
I wonder if the producers of the National Treasure sequel were aware of that when they decided to place their treasure there.