One of the largest caverns in the world has a maw large enough to stack cathedrals in.

The Hanshin Expressway goes right through its 5th, 6th, and 7th floors.

This Japanese national treasure was originally built in 593.

A plaque marks the site directly below the mid-air detonation of the atomic bomb over Hiroshima.

Peace Park and the Atomic Bomb Dome.

A Bohemian "anti-hotel" offers off-kilter stays in Sri Lanka.

This elaborate temple was built around one of the Buddha's teeth.

Hundreds of Buddhas in a re-discovered Indonesian temple.

Subterranean place of worship in Indonesia.

A giant Troll lurks under one of Seattle's oldest bridges.

This former coal gasification plant found a curious second life as a popular public park.

A museum dedicated to the history and exploration of both popular music and science fiction.

A wall of chewing gum moonlights as collective art.

Couple's personal collection of pinball machines turned public pinball museum.

This attraction was abandoned after the Chornobyl disaster.

The ghost town left by the worst nuclear disaster of all time is being taken over by nature and urban explorers.

The deepest metro station in the world.

Physicist’s epitaph provides final confirmation to a career of turmoil.

The topiary maze at the Habsburg hunting lodge.

Apartment complexes built into huge repurposed natural gas tanks.

Vienna's giant wonder wheel had a starring role in one of the greatest noir movies of all time.

A spherical "micro-nation" in the heart of Vienna.

Op-art architecture designed for happiness.

Giant WWII fortresses that fired 8,000 rounds a minute, now home to thousands of pigeons.