An ancient passage filled with stalls selling used books, once frequented by Vincent Van Gogh.

The world's only museum devoted to the wonders of fluorescence.

A huge collection of rocks, gems, and crystals.

An urban laboratory.

Before serving as James Bond's Casino Royale, this Victorian-era spa catered to the world's elite.

A subterranean display of public art and architecture.

A massive, abstract lookout tower providing a panoramic view of Prague.

Bohemian paradise covered in majestic forests.

An unusual bronze bus shelter is actually an art installation commenting on the city's history with the Nazi party.

Abandoned substation turned village treasure.

Eons ago, a rushing lava river formed this pristine passage through solid rock.

This unique library spans a mighty river.

Machinery left over from California's once thriving mercury industry now attracts artists and explorers.

A two-inch thick solid brass rod that extends an astounding one kilometer straight into the earth.

The only subway station in the city that still makes use of gap fillers.

Mysterious ancient petroglyphs carved on a glacial boulder at the tip of Bainbridge Island.

This contemporary art museum is filled with other, smaller museums, which feature work from artists primarily in the Pacific Northwest.

A miniature rainforest is growing inside of a Midtown Manhattan office building.

A secret door leads to this cozy dive that sells only “milk.”

Five varieties of trees with custom-designed grates around the trunk are planted along the route of the Seattle Transit Tunnel.

This three-story antique market and curiosity emporium claims to be "the largest singly owned antique shop in the Pacific Northwest."

More than 300 years ago, a revolt at this Hopi pueblo shaped the future of the American Southwest.

A surreal landscape where fanged rocks rise from the ground and the ocean feels like a great mystery.

A Victorian marvel of engineering is now a 21st-century tourist attraction.