The world's second-largest excavated hole.

A serpentine highway twists and turns over the treacherous Norwegian Sea.

A geological bull's-eye visible from outer space.

Rock-cut caves and 7,000 Buddhist sculptures carved into the nearly sheer face of a sandstone mountain.

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

Hundreds of wooden coffins dangle from cliffs and caves in the Philippines.

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

This "floating island" plateau sits 7,671 feet above the forest floor.

A 19th century artistocrat's mansion, turned into a library, hidden in a modern library.

The remains of diamond fever taken over by the desert.

A countryside Romanian cemetery filled with colorful crosses bearing lyrical, ironic, or satirical rhymes.

White beach sands made of the remains of tiny, star shaped creatures.

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

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

An architectural marvel that spans the Arda River, and has stories of a haunted past.

Stunning examples of Russia's 18th-century wooden architecture.

This extraordinary geological oddity resembles human-made pavement.

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

A gravity-defying "devil's bridge" that has a surprising architectural feature for its stability.

This stunning Brazilian library contains the largest collection of Portuguese texts outside of Portugal itself.

Not one, not two, but three natural bridges remain in this captivating spot post-sinkhole.

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

Earth's tallest volcano is sacred to Native Hawaiians, and home to a dozen world-class observatories.

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