Surreal riveted sea forts once protected the Kent shores from German attack.

Yale University's home for rare works, including the mysterious Voynich Manuscript.

A mysterious castle built as a monument to lost love.

An underwater city for the dead.

An immersive environment that is part haunted house, part choose-your-own-adventure, and part jungle gym.

Tubing through a cave lit with glowworms is a magical underground experience.

Abandoned railway line circling the city of Paris.

Possibly the most beautiful carillon in the world, set atop Iron Mountain in Florida.

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

The crypt of the imposing Stephensdom holds royal intestines and thousands of skeletons.

This attraction was abandoned after the Chernobyl disaster.

The deepest lake in the United States, and once the site of epic destruction that lives on in legends.

This abandoned Navy base was transformed into an off-grid alternative living community for thousands of people.

A nearly 500-year-old sculpture depicts a man eating a sack of babies, and no one is sure why.

One of the few remaining casualties of the London Blitz, this destroyed church has become an enchanting public garden.

The beautiful baroque library of the Hapsburg empire.

Furniture tries to escape an abandoned building in San Francisco.

One of the tallest buildings in Iceland, and perhaps, the most visually impressive.

This beautiful natural train tunnel is said to grant the wishes of visiting lovebirds.

Natural time capsule containing an alien ecosystem.

Ruins of a German Castle on top of a towering stone pillar.

An alchemist's "magic door" stands in the middle of a Roman park.

Carved by a waterfall in a hard-to-reach rock formation, this heart-shaped rock has inspired romantics for decades.

One person's lost luggage is another person's treasure.