
Why is a South Dakota “Tunnel to Nowhere” One of U.S.’s Greatest Places?
All controversies aside (because as we all know, there are many) Mount Rushmore was and remains an astonishing achievement by sculptor Gutzon Borglum and his son (interestingly enough) named Lincoln.
Many people, however, don't know that there is a secret tunnel just behind Lincoln's head (Abraham Lincoln that is, not Lincoln Borglum) that has been named one of the Greatest Places in the United States.
Sculptor Borglum believed that in time people would forget the meaning behind Mount Rushmore and that its importance would fade in the American consciousness. So he wanted an addition to the monument which would ensure that didn't happen.

Borglum was fascinated by monuments from other great societies like the pyramids of Egypt. He wanted something that would last as they had - -to be discovered by other civilizations.
He liked the idea of a giant monument with an explanation of what it was, why it was there, and what it stood for in a secret area behind the monument. That was the birth of the Hall of Records idea.
He had an ambitious plan for a whole campus, including a grand staircase leading to the Hall of Records. He saw stately display cabinets with important documents, like the Constitution, Declaration of Independence, and more, held within them.
Funding was always an issue for this project. Work would begin and stop according to government and private funding coming and going. Then when World War ll began, Congress let Borglum know they needed the money they had appropriated for the project, for the war effort. So they told him to finish the heads, forget the rest, and that signaled the end of the Hall of Records.
In 1998 Borglum's daughter had a time capsule of sorts buried at the entrance to the tunnel. It contains a "history of the United States and biographies of all four presidents" and her father.
Very few people have seen this "secret tunnel" behind Mt. Rushmore without the permission of the National Park Service, and to be honest there isn't a whole lot to see in the unfinished condition in which it remains.
Sources: National Park Service, Only in Your State and Discovery UK via youtube