Large, airy hallways hide within an impenetrable fortress that beckons urban explorers.

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

An ethereal glowing blue ocean cave in Croatia.

A gift from Emperor Franz Joseph I to his wife.

Fantastic stories on a miniature railroad.

American soldiers discovered Europe's best one-liner at the end of World War II.

Ugly 18th-century dwarf statues living in a perfectly landscaped Austrian garden.

This series of underground chambers contains Europe's largest subterranean lake that is slowly drained each day.

Visitors dip into a variety of pools of what was once ice.

Each year melting snow turns these Austrian hiking trails into scuba zones.

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

A small museum filled with over 1,000 clocks, and one particular clock calibrated to run until the year 9999.

This Viking Age memorial contains the oldest known image of a Täby resident.

These two springs are tied to several legends, one of which involves the travels of Saint Olof.

An oil drilling mistake created this fountain that has been spraying water for over 150 years.

Believed to be the country's tallest waterfall, the Njupeskär is actually much smaller.

The 19th-century home of Count and Countess von Hallwyl is now a museum.

This serene wooded hilltop has a dark history as the climactic point of the Swedish witch trials.

This patch of land is home to Sweden's largest burial mound, allegedly belonging to a mythical king.

This collection of Dwarf beech trees were once believed to be enchanted trolls in disguise.

A botched 18th-century canal silenced one of Sweden's most magnificent waterfalls.

A Bronze Age stone ship said to be the grave of the mythical founder of Gotland.

This pyramid in southern Sweden houses the remains of an eccentric nobleman, who spent his life doing whatever he felt like doing.

Sweden's southernmost prehistoric rock art is hidden just outside Gothenburg.