The remnants of two World's Fairs are here, complete with a 12-story globe, a mini-Manhattan, and a UFO-shaped pavilion.

The haunting, dilapidated remains of a former poorhouse on Staten Island's Greenbelt.

This frozen tunnel in central Alaska is both an engineering feat and a valuable climate classroom.

This Great Depression-era creation was once known as the strangest house in the world.

This former coal gasification plant found a curious second life as a popular public park.

An abandoned Nazi explosives plant founded by the inventor of dynamite is now an underground museum.

Three bridges straddle a stream, one stacked upon the other.

This jaw-dropping 19th-century bridge uses its reflection to form what appears to be a perfect circle.

Over 20,000 sets of spice shakers reveal the surprisingly telling history of our most basic spices.

It took more than 20 years and a sharp eye for one man to assemble this quirky collection.

The humble horn finally finds a place in the sun.

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

A gigantic sculpture garden is packed with innovative oddities.

Dedicated to the unsung history of human waste.

This scalding hot river was thought to be a myth until one geoscientist made it his quest to study the mystical waters.

An acoustic anomaly with a mysterious cause.

The ancient settlement attracts tourists from all over looking to learn about the Chinese vision of the afterlife.

The deepest hole drilled in the name of science, where evidence of Precambrian life was found.

A special train service transported Sydney's dead from this station to "Necropolis Receiving Houses" at Rookwood Cemetery.

A collection of haunted artifacts chronicles the career of the world's most famous paranormal investigators.

A rusted metal giant pays tribute to Birmingham’s industrial past.

All that remains of Jacques Cousteau's 1960s underwater "village."

Where America's first doomsday cult awaited the end of the world.

The world’s largest truck stop includes a barber shop, chiropractor, and a huge museum with antique trucks.