The remnants of an early American attempt at missile defense.

Believed to have once stored either human remains or rice wine, thousands of mysterious stone jars lie in ruin.

An Aztec snake god has taken the material form of an apartment complex.

A windswept necropolis carved into the rocks overlooks the "most Portuguese town in Portugal."

Houses are tucked between, on, and underneath giant boulders.

A vertically floating hemlock controls the waves and weather at Crater Lake.

This massive underground salt mine now holds a sci-fi theme park in its depths.

This massive World War II calculator hearkens back to the days when "computer" was a job title.

Retirement home for giant obsolete machines.

Hundreds of secret cabinets built into the walls of legendary poisoner's private work room.

This modern French ossuary contains the jumbled bones of 130,000 WWI soldiers.

This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.

Eco-village hidden in the foothills of the Alps that created a massive system of psychedelic underground temples.

Rent out a glass igloo to watch the Northern Lights like you live in the future.

150-year-old satirical tableaus made from stuffed frogs.

This odd Chilean waterfall-cano hotel must be entered via a rope bridge.

Perfectly preserved ancient monastery in an impossibly dramatic location on a rocky island in the Atlantic.

Cold storage for agricultural biodiversity.

Turnip-shaped island just off the Michigan shore in Lake Huron.

If a glacial river suddenly diving into a sheer chasm via a dramatic, multi-stage waterfall isn't peak Iceland, it's certainly close.

A 300-yard long natural tunnel runs through a ridge deep in the Appalachian Mountains.

This lake in the Cascades lives up to its name, disappearing down a hole every spring.

Eons old volcanic activity created one of the most stunning rock formations in the United States.

A breathtaking array of ancient Pueblo structures and artifacts counterintuitively preserved by neglect.