The underground facility beneath the dam is a hot spot for conspiracy theories, but even weirder is that dozens of bodies are believed to have been buried within the concrete structure, as there were over 100 deaths during its construction.
An artist named Jim Sanborn created this sculpture called Kryptos, and while many have tried to solve the encrypted message, it still remains one of the most well-known unsolved codes in the world.
See also: Can you identify these famous landmarks from an unusual perspective?
An antique train car is still parked in the tunnel beneath one of New York City's most luxurious hotels. Rumor has it, the abandoned track is still used to transport celebrities and other notable guests to and from the hotel.
The exclusive restaurant is hidden behind an unmarked door in the New Orleans Square, and it's the only place in the park that sells alcohol. But don't book your trip unless you have the $25,000 required to join the club, plus the minimum annual fee of $10,000.
Disney has become a famous American landmark over the years, and while even hardcore fans might know some secrets of the park, very few are privy to the prestigious and secret Club 33.
Borglum was only approved to create a Hall of Records, a chamber intended to hold some of America's most treasured documents, behind the hairline of Abraham Lincoln. Unfortunately, the sculptor died before completion.
Its vaulted ceilings, stone fireplace, century-old leaded glass, and high-end cocktails pay homage to a Jazz Age financier who converted the space to a reception hall in 1923. It's also a popular celebrity destination!
Surprising secrets hidden in American national landmarks
You're about to see a whole new side of the country
LIFESTYLE Curiosity
America's tourism has flourished and thrived since its pioneering days, and each second, thousands upon thousands of people are snapping photos of popular landmarks without even an inkling of the incredible secrets they're looking at. Don't be one of those people! Check out this gallery to find out what's hiding beneath the rock, behind closed doors, and right under your nose at these popular landmarks.