This fantastical house shaped like a seashell brings aquatic design to architecture.

The largest cave shaft in the world is home to thousands of birds and popular with BASE jumpers.

Hotel designed around a 16th century Mexican bullring.

The mysterious, fantastical woodland inspiration for "The Lord of the Rings."

This massive subterranean fissure is known as the "underground Grand Canyon."

A castle built for love, and abandoned due to heartbreak.

A swing to dangle you off the very edge.

An ultra-modern vista that has been featured in so many films the house is a celebrity in its own right.

The summer home of the largest colony of bats in the world.

Breathtakingly blue walls shimmer inside the "Glacier Behind the Town."

An extraordinary natural landscape of mountains, waterfalls, and rocky cliffs riddled with tunnels.

This picturesque mansion has gone from opulent ruin to nature museum.

The largest game reserve in Africa is home to thousands of species but refuses to house humans.

European castle ruins in an American state park are actually the product of death and grief.

This legendary city has been a tourist attraction for centuries.

A popular swimming hole that hides one of America's most deadly diving spots.

Home to 10,000 medical specimens including the remains of Rudolf Virchow's extensive collection of pathological specimens.

One of Ireland's most infamous prisons for rebels including men, women and children.

Stripes of flowers bloom each spring in a 50 acre rainbow of color.

Wedged between two buildings at the Great Ormond Street Hospital is this secret music installation.

Each spring, a dreamlike carpet of bluebells overtakes the forest floor.

A clear blue swimming hole with hidden caves, still unexplored.

Huge stone depressions which may have acted as an Incan agricultural experiment.

Two geological phenomena in one precarious locale: a towering stone window, and a deep blue void.