South Dakota historian Doane Robinson conceived the monument in 1923 as a tourist attraction - originally proposing to carve Western heroes like Buffalo Bill and Lewis and Clark into the granite needles of the Black Hills. He recruited sculptor Gutzon Borglum, who had grander ambitions.

Borglum selected Mount Rushmore for its smooth granite and southeastern exposure. He chose presidents representing the nation's founding, expansion, preservation, and development. The original design included the presidents' torsos, but funding ran out before they could be carved.

The Black Hills are sacred to the Lakota Sioux - Paha Sapa, the heart of everything that is. The 1868 Treaty of Fort Laramie granted the hills to the Sioux 'as long as grass shall grow and water flow.' In 1877, after gold was discovered, the US seized the land.

In 1980, the Supreme Court ruled the seizure was illegal and awarded compensation. The Sioux refused the money (now over $1 billion with interest), demanding the land's return instead. Mount Rushmore sits on stolen land.

Construction began October 4, 1927, and continued until October 31, 1941. Workers hung from harnesses on the cliff face, drilling holes and setting dynamite charges. Ninety percent of the carving was done with explosives. Fine details were finished with jackhammers and hand chisels.

The work was dangerous - workers descended in bosun's chairs 500 feet above ground. Remarkably, no one died during construction, though silicosis from rock dust later killed many workers. Gutzon Borglum died in March 1941; his son Lincoln completed the project seven months later.

Each face is approximately 60 feet tall. Washington was carved first (1930-1934), positioned to catch morning light. Jefferson was started to Washington's right but moved to the left after flawed rock was discovered. Lincoln emerges from the mountain's shadow. Roosevelt sports his iconic pince-nez.

Original plans called for inscriptions, a Hall of Records behind the faces, and carved figures to the waist. Budget constraints ended the project before these could be completed.

Mount Rushmore draws 2 million visitors annually - one of America's most visited monuments. It appears in films from North by Northwest to National Treasure. It's an instantly recognizable American icon.

But the monument remains controversial. To many Native Americans, it's a monument to colonization carved on stolen sacred land. Like America itself, Mount Rushmore is complicated - beautiful and troubling, inspiring and shameful, a monument that means different things depending on who's looking.