A vista of the city and sea from atop the little-known viewing deck on an unassuming Columbus statue.

This semi-secret storybook hedge maze is also the oldest garden in the city.

One of Europe's largest supercomputers is housed inside of a disused chapel.

Turntable anonymously received orphans, alms, and groceries.

The 2,000-year-old Roman columns are hidden within Barcelona's Gothic Quarter.

A stately palace has been converted into the world's largest cannabis museum.

Barcelona's historic 19th-century sewers, whose foundations were laid in medieval times, are open to the public for exploring.

A haunting collection of the vanished and disappearing natural world.

Known as the "Dodo Manège," this carousel features a herd of animals that have disappeared—or may be gone soon.

A museum dedicated to linguistics, from how babies learn to talk to endangered and extinct languages.

A tribute shrine where the Space Invasion street art movement started.

One of Jeff Koons’s largest sculptures and his first commemorative work.

The narrowest street in Paris.

The curious underground history of keeping Paris clean.

Paris' fabled purveyor of exotic taxidermy and natural history curios.

This Parisian café sticks almost exclusively to an ethos of reuse.

Hidden inside this Arizona fast food franchise is an in-depth exhibit on the famed WWII counterintelligence program.

These mid-century motels once housed the workers who built the Glen Canyon Dam.

Dramatic river bend surrounds a natural red-rocked pedestal.

Archaeologists believe this panel of petroglyphs depicting descending sheep and other figures in Glen Canyon are 3,000 to 6,000 years old.

Walk through the sets of old western films at this small museum in Utah.

The Grand Canyon’s original airport, which once welcomed pilots like Amelia Earhart and Charles Lindbergh, lies abandoned.

This secluded aqua waterfall in the Grand Canyon is the perfect swimming hole, and the Havasupai tribe's fiercely protected natural wonder.

More than 25 fully functional scale replicas of famous lighthouses dot the shores of Lake Havasu.