Resting in the middle of an Austrian river, this sci-fi "island" lets people cross in neon style.

The shell of a medieval fortress offers commanding views of the area it once protected.

Austria's ultra-modern art museum looks like Cthulhu's giant alien heart.

One of the largest caves in the world open to the public.

The prototype for all Nazi concentration camps.

A copy of the Statue of Liberty greets visitors to the birthplace of Auguste Bartholdi.

Climb inside an iron crystal magnified 165 billion times its normal size.

A 14th-century fortified keep showcases the masterpieces of an ingenious 20th-century clockmaker.

This centuries-old gothic monster has been converted into a sprawling, glossy bookstore.

This Danish rock field is actually a sprawling ancient cemetery holding the bodies of 700 Vikings.

If they push on just the right spot, even the weakest person can move this titanic boulder.

Fantastic stories on a miniature railroad.

The comedy and tragedy of Oscar Wilde is preserved in a Dublin park, captured in a sculpture of colorful stone.

An abandoned lighthouse awaits its destiny: being buried under shifting sand.

The Bristol Camera Obscura housed in an ancient windmill.

The world's tallest church tower reveals a spectacular view to anyone up to the task of climbing the daunting staircase.

The northernmost point in Denmark is a turbulent sandbar created by two clashing seas.

Perfume museum and library.

Old Danish castle immortalized in Shakespeare's Hamlet.

This fairytale castle was built as a show of power but was nearly torn down thanks to its history of torture.

A miniature train-ride through Slovenia's largest cave system.

Swarovski's museum/theme park is a fake diamond fantasia overlooked by a giant.

Scattered throughout London are ancient remnants of the city's former bounding wall.

Castle and secret tunnel withstood a siege until its owner was killed by the Holy Roman Empire, while sitting on the toilet.