An ancient Viking runestone hidden in plain view in Stockholm's old town.

It houses the remains of a 17th-century version of the Titanic.

The library's graceful rotunda is like a bibliophile's temple.

This floating sculpture of ice is a poignant reminder of nature's power.

World's strongest whirlpool.

A serpentine highway twists and turns over the treacherous Norwegian Sea.

The final home of the legendary Danish sailor said to have lived to be 146 years old.

The world's first combination ski slope and power plant.

An old Danish political institution where members of government can grab a drink off the record.

Dozens of musicians have planted trees in this Danish park, and donated songs to go with them.

A public display of random paleontology.

From buck blood to Theriak miracle tonic, this collection of Renaissance chemist's gear look's like a wizard's pantry.

A perfectly circular stronghold constructed in the 10th century is now a nucleus of Viking culture housing a museum, village, and reenactment of an epic Viking battle.

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

Climb to the top of its spiral spire for spectacular views of Copenhagen.

Vortex-shaped aquarium hosts Europe's largest school of piranhas and other ocean creatures.

This colorful artistic feature atop a Danish art gallery allows visitors to stroll through a rainbow.

This icon of the Atomic Age now lays dormant.

The de facto symbol of Copenhagen is this bronze fairytale which cannot seem to keep its head for very long.

Copenhagen's celebrated theme park and gardens.

A unique workspace where offices reside on pirate ships and inside gingerbread houses.

A quirky collection of outsider art made from automobile parts.

The universally beloved children's television figure is interred on a high hilltop in one of western Pennsylvania's oldest cemeteries.

One of the steepest streets in the United States makes an intriguing challenge for cyclists.