The 5th Head?

Image result for rushmore mystery

While it is quite a lesser known fact, but when the son of Doane Robinson took over his father’s project, he had plans to add another face amongst the president, the one of his father’s. But as one can imagine this idea of his didn’t go well with the common public or the investors of this project. Though he couldn’t immortalize his father amongst the presidents he did so in a secluded area not very far from the actual mount Rushmore.