Looking like they're either emerging from or being absorbed by the mountain, the stony faces of past presidents George Washington, Thomas Jefferson, Abraham Lincoln and Theodore Roosevelt - carved 60ft tall in the granite of a Black Hills outcrop - are one of the most famous images in the USA and the top attraction in the state; the monument gets nearly three million visitors each year.
You can't help but be impressed by its sheer scale and the massive physical effort of the team (led by sculptor Gutzon Borglum) that created it between 1927 and 1941.
