What's Inside Mount Rushmore's Not-So-Secret Chamber?

Mt. Rushmore, secret chamber — Behind the giant faces on Mount Rushmore in the Black Hills region of South Dakota, there lies a chamber that's off limits to the public. Scott Olson/Getty Images

If you saw the 2007 movie thriller "National Treasure: Book of Secrets," you probably remember the part about South Dakota's Mount Rushmore containing a secret passageway that leads to a long-buried city of gold, which President Calvin Coolidge tried to conceal by having sculptor Gutzon Borglum carve 60-foot (18.3-meter) faces of four U.S. presidents, into its granite.

Okay, before you get too excited, that was just a movie. There's no gold under Mount Rushmore. But there is a 70-foot (21.4-meter) passageway carved inside the mountain, and while it's not quite top secret, the space — which isn't open to the public — does have a strange story.

The tunnel was created in the late 1930s by Borglum, as part of what he envisioned as one of the most important features of the monument — an 8,000-square-foot (743-square-meter) man-made cave that would contain bronze and glass cabinets filled with replicas of the U.S. Constitution and other significant documents and artifacts from U.S. history stamped on aluminum sheets, along with busts of famous Americans and exhibits extolling U.S. scientific, industrial and artistic achievements.

Hall of Records

The Hall of Records, as he called it, would have a 20-foot (6.1-meter) entrance with glass doors and a bronze eagle stretching 15 feet (4.6 meters) from talons to crest above it, along with the motto, "America Marches On." To provide access to the hall, Borglum planned to carve an 800-foot (244-meter) granite stairway up the backside of Mount Rushmore, according to this 1975 National Park Service historical study.

The chamber was part of Borglum's grandiose vision to create a monument that would survive for millennia to remind future generations of the United States' greatness. "Borglum was enamored with the pyramids and the Colossus of Rhodes, and other monuments of the ancient world," explains John Taliaferro, author of the 2002 book, "Great White Fathers: The Story of the Obsessive Quest to Create Mount Rushmore."

"He wanted it so that thousands of years into the future, people would not just see these heads, but have the manual and all the pieces to reassemble the American civilization — the ideas, the words, the blueprint," Taliaferro says.

As Borglum explained in a 1939 letter quoted in the NPS study, his goal was "that one great record should somewhere be made that would — even ten thousand years hence — tell the people of what manner of men invented and built the great West World Republic."

Borglum's vision of future people someday happening upon his repository of America's long-vanished greatness eerily brings to mind the climactic scene of the 1968 film "Planet of the Apes," in which the astronaut played by Charlton Heston ventures into the forbidden zone and discovers the Statue of Liberty, embedded in the sand.

"It was sort of part fallout shelter, part time capsule," Taliaferro says.

But Borglum also wanted the Hall of Records to be impressively ornate, with fluted columns and a cathedral ceiling. He was inspired by Hollywood sets of the sort created for Cecil B. DeMille's cinematic epics, according to Taliaferro. Over time, according to the NPS historical study, the plan grew even more elaborate, with five or six more rooms on a lower floor beneath the main hall.

Borglum's Death and WWII

The sculptor never really calculated how much the Hall of Records would cost, which contributed to the project's undoing. Congress, which had stepped in to fund the memorial, balked at giving him a blank check, and work on the hall was halted in 1939 after legislators directed that the faces of the presidents were the only parts of the monument that should be completed. After Borglum's death and the U.S. entrance into World War II in 1941, work on Mount Rushmore was suspended altogether. The tunnel was the only part of the Hall to be completed.

But the sculptor's daughter, Mary Ellis Borglum, had a passion about at least partly completing her father's vison for the Hall of Records. At her urging, the Mount Rushmore Society, a nonprofit organization that supports improvements at the national memorial, raised $250,000 to create a vault inside the passageway, and fill it with 16 porcelain enamel panels. According to NPS, some of the panels tell the story of Mount Rushmore, the reasons why the four Presidents were chosen to be depicted on the mountain, and provide a short history of the United States as well. A 1,200-pound (544-kilogram) capstone protects the panels.

"This repository is not accessible to visitors but is left as a record for people thousands of years from now who may wonder how and why Mount Rushmore was carved," NPS explains. Gutzon Borglum finally got what he had wished for.