Dine on food tied to Viking history and legend at this subterranean Stockholm spot.

Bring your hiking shoes, wool socks, and thermal underwear for a stay in these cozy forest huts.

Stockholm's decidedly unique public transit system has doubled as the world's longest art gallery for decades.

This monument is a stark reminder of the horrors of the Zanzibar slave trade.

Go inside a revolutionary, cage-less zoo where 70 species of monkeys roam free alongside their human visitors.

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

A beautiful maze marks where three countries meet.

A beautifully eclectic mix of architectural styles.

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

A little sculpture with a large wardrobe.

Visit the ancient, mysterious Roman catacombs ... in the Netherlands.

The ruins of this Dutch castle sit atop a labyrinth of once-secret tunnels and passageways, dating back over 900 years.

An amusement park on the grounds of an unused nuclear power plant, with a swing ride inside the cooling tower.

This fairy tale forest hides scenes from some of the more obscure and bizarre Western nursery stories.

The largest 19th century panorama in the world still in-situ.

A grassy pyramid named after a French battle.

A desert ghost town—occupied for only 12 years—was once home to more than 500 silver mines.