Longest canal tunnel in the world, abandoned in the 1960s.

Once thought to be the oldest living tree in the world, Methuselah was germinated before the Egyptian pyramids were built.

An unoccupied lighthouse encased in layers of ice from the waters of Lake Erie.

Inside an old airplane hangar, friends and strangers alike play on a massive trampoline.

Sculpture designed by Turkish artist and professor Mehmet Ali Uysal.

The birthplace of an eccentric alchemist and possible inspiration for the fictional reanimator of monsters.

Prehistoric park filled with the fossils of dozens of extinct species including Australian megafauna.

This Nazi-built amphitheater was constructed on a sacred mountain site used by various German cults.

Rome's semi-secret peephole vista is also a former Crusader stronghold.

Berry Gordy Jr.'s old home was the original headquarters of Motown Record Corporation.

Copenhagen's celebrated theme park and gardens.

Over 3km of caverns and caves at the Switzerland-France border contain the largest underground river in Central Europe.

Mysterious lost empire of the Silk Road.

The oldest Italian café in Boston, this spot also serves as a veritable museum of vintage coffee ephemera.

Authentic gondola hanging from the ceiling, notable mural in the back room.

A famous alternative culture epicenter and where Joplin serenaded young hippies.

Legend says this cave housed a 16th-century cannibal and his family of 48.

A treasure hunter's tiny bar, harboring celebrities since 1959.

Narrow-gauge railway with its own personal power grid.

Moonbows over Kentucky.

Egyptian treasure trove of fossils documenting the whale's transition from land mammal to sea creature.

A roaring, awe-inspiring double cascade of icy water flows through woodland Oregon like something out of a Tolkien novel.

Constantly maintained, this organ is playing a six-century long composition by John Cage.

Providing the soundtrack to the golden years of the Seattle grunge scene.