Abraham Lincoln holds the history of our country’s past.

Literally.

Tucked inside Lincoln’s frontal lobe in Mount Rushmore in Keystone, South Dakota is a secret, inaccessible-to-the-public chamber.

The vault was designed by the monument’s sculptor, Gutzon Borglum, who envisioned it as a room dedicated to the history of the United States.

The National Park Service details that Borglum wanted a written history of America’s greatest historical hits to go along with his four-headed sculpture, including an 800-foot stairway with a large bronze eagle – who’d have a 38-foot wingspan — at the entrance. Above the eagle an inscription would read, “America’s Onward March” and “The Hall of Records.” Carved into the walls would read America’s nine most important events from 1776 to 1906 Busts of famous Americans would line the hall, as well as a list of US contributions to art, science and industry.

Unfortunately, Borglum died in 1941 and never saw his vision come to life. But in 1998, monument officials revived Borglum’s dream of the room acting as a vault for America’s history.

Today, sculpted into a series of porcelain enamel panels, is the story and history of Mount Rushmore, along with an explanation of why Washington, Jefferson, Roosevelt, and Lincoln were chosen. There are also panels sculpted with the words to the US Constitution, the Bill of Rights, and the Declaration of Independence, and park officials even included a biography of artist Borglum. They’re all kept safe inside a titanium repository behind a giant, 1,200-pound granite slab.

The chamber is way too difficult for tourists to access, but no matter what catastrophes the future millenniums hold, the history of America is safe inside Honest Abe.