A massive underwater sinkhole made famous by Jacques Cousteau.

Find out what it sounds like when doves cry at Prince's recording studio estate turned museum.

Equal parts record-breaking temple to consumerism and bizarre fun park, it's more than you think it is...

A giant, Gilded Age mansion that once belonged to the beer baron of Milwaukee.

This striking art museum holds an amazing series of curiosity cabinets.

Statue dedicated to the star of an old television show.

A place to eat for on-the-run agents and espionage enthusiasts.

Erosion and time have created a naturally-formed water park.

Giant granite rocks standing end-to-end like a train of circus elephants.

400 million-year old limestone caverns nestled in the Ozarks served as shelter and a hideout for cultures throughout North American history.

The world's largest man-made underground caverns offer unparalleled underwater wonders.

Famous church recognized for both its unique design and disciplined monks that live according to the Benedictine discipline.

This titanic oil company sign is a reminder of the Americana boom of the 1970s and also its commoditization.

This mausoleum is the final resting place of one of St. Louis's richest and most tragic families.

A creepy sculpture of a decapitated head invites viewers to see St. Louis through its empty eyes.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

The youngest volcano in Central America.

The crumbling remains of a once-grand building.

This staircase full of Mayan hieroglyphics is perhaps the largest single text in the world.

One of the tallest buildings in Iceland, and perhaps, the most visually impressive.

Home of the unusual art of water puppetry, one of Vietnam's oldest curiosities.

The notorious "Hanoi Hilton" where Vietnamese colonial subjects and later American POWs, including John McCain, were imprisoned.

Ho Chi Minh's perfectly preserved body has been on display here since 1975.

This Singaporean food-court stall was home to the world's cheapest Michelin-starred meal.