An abandoned Incan construction project left behind a mysterious "doorway."

A Hawaiian stairway to heaven—that you can't climb.

The world's only international cryptozoology museum is host to an unrivaled collection of mysterious objects.

The ancient dwellings of the Puebloans, located in the cliffs of majestic mesas.

The largest stone moai on Rapa Nui.

An ancient capital city that dates back 3,000 years old and harbors many surprises.

The Cadillac Ranch for monster truck aficionados.

A massive underwater sinkhole made famous by Jacques Cousteau.

The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

A sculpture of a giant hand reaches for the stars in the middle of the Atacama desert.

Death road of Bolivia.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

Mysterious ancient boulder carved with petroglyphs in the mountains of Western North Carolina.

Every equinox this Maya pyramid puts on a spooky ancient light show.

In the middle of an extremely unforgiving and desolate high desert is the most secret military facility in the world.

The only structure left with direct ties to the Salem witchcraft trials of 1692.

These rows of World War II-era bunkers were the scene of some of the infamous Mothman sightings.

The largest island on the great salt lake is home to curious creatures and strange stories.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

An Amsterdam street lined with antique shops each one dedicated to a different obscure collection.

A museum dedicated to the alleged Roswell Incident.

The world's highest and most dangerous infinity pool lies at the precipice of Victoria Falls.

A peculiar mansion built by the troubled heir to the Winchester Rifle Company fortune.

"Dark Sky Park" is heaven on Earth for astronomers, one of the rare U.S. locations with no artificial light pollution.