Mount Rushmore is one of the most visited sites in the United States with more than 3 million visitors every year. A secret room that was destined to hold the most important texts from American history is hidden behind the head of President Abraham Lincoln. Unfortunately, visiting this archive room is forbidden to tourists. It is sealed with a big 500kg granite door. Currently, it contains a wooden chest containing the American Constitution, the Declaration of Independence, as well as a biography of Gutzon Borglum, the creator of the monument. Created in the 1930s, Gutzon Borglum already had the idea to build a safe room for the United States. But when he died in 1941, the creator never got to see his idea come to life. More than 50 years later, in 1998, those responsible for the monument decided to go through with his basic idea and moved these documents here.