The hidden room at Mount Rushmore has been an enduring urban legend.
But pictures circulating this week have illustrated what many have always known: there really is a secret passage there.
Found behind the granite sculpture of Abraham Lincoln is the Hall of Records, built by architect Gutzon Borglum.
His true dream was never realised at the (already incredibly elaborate) memorial – he intended for the passage to be far grander.
But if hidden doors and secret passages are your thing, there are plenty across the world to go hunting for.