Britain's oldest and biggest hole in the ground.

"Only the devil could play golf here."

Partially collapsed lava tube and cave system complete with concert hall, underground pond, and unique albino crabs.

A seemingly endless landscape of pure salt stretches far across Bolivia.

Legend holds eating just one of these black eggs can add seven years to one's life.

This abandoned Navy base was transformed into an off-grid alternative living community for thousands of people.

A massive underwater sinkhole made famous by Jacques Cousteau.

A collision of human error and natural geothermal pressure created this rainbow-colored geologic wonder.

Native American burial mounds? Giant gopher dens? No one knows what created the Mima Mounds.

England's most notorious suicide spot.

Hoodoos, naturally eroded land formations, stand 20 feet tall in the Canadian badlands.

The most alien-looking place on Earth.

The lake that fills and empties itself at random.

When you get to Magnetic Hill park near the sign, put your vehicle in neutral gear, and watch it roll uphill...

Ornate limestone building now filled with geologic specimens, and more.

A spectacular cave and a beguiling lake.

Stalactites and stalagmites in a beautifully lit cave.

Mysterious rocks that ring musically when struck.

These mysterious ancient stone spheres were created by a civilization lost to time and are now mostly lawn ornaments.

This solitary monastery may hold the remains of Vlad the Impaler (but probably not).

This hospital fell into ruins after failing to act as the advocate for the mentally ill it was designed to be.

An abandoned water park overtaken by the dunes.

Natural time capsule containing an alien ecosystem.

The rocks in this arid basin leave trails of movement behind them.