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

A haunting collection of the vanished and disappearing natural world.

An underground mansion with fruit-bearing trees and grapes growing beneath the surface of central California.

Ruined 11th century abbey built by King David I in Edinburgh, Scotland.

Long-abandoned trolley tunnels just a mile away from the White House are turning into an art space.

Museum preserving torture methods from the past.

A surreal museum of extraordinary industrial objects.

Franciscan monks created a facsimile of the Holy Land for North Americans who couldn’t afford the trip overseas.

Once the most densely populated place in the world, this island is now a ghost town.

One of the world's oldest and most massive living organisms is a grove of quaking aspens.

This upscale streetwear store is hidden behind a fake Snapple machine in the back of a deli.

A "gravitational anomaly" located in the redwood forests just outside of Santa Cruz, California.

Where manatees are the snowbird vacationers in these balmy Florida springs.

This abandoned asylum was once a state of the art facility before devolving into one of the most deadly mental institutions in American history.

An Australian lake whose pink hue defies scientific explanation.

This frequently-photographed waterfall takes only a short hike to visit.

Take a drunken tour inside the world's largest known geode.

Seemingly grown on some other world, these New Mexico rock formations look like a disused science fiction set.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

An abandoned facility that has become a place of ritualistic satanic worship, or so rumor has it.

Hollowed out cedar log tubs set in an ancient towering forest.

One of the oldest medical collections in Europe focusing on rare surgical instruments.

A pair of slides and a tree-lined stair corridor have been an urban oasis for nearly 40 years.

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