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

An enormous, inside-out glass globe built in 1935.

Wondrous sandstone hoodoos where Native Americans collected clay for pottery, 9,000 years ago.

Dramatic river bend surrounds a natural red-rocked pedestal.

A treasure trove of artifacts, books, and artwork from the "golden age" of exploration.

This jaw-dropping 19th-century bridge uses its reflection to form what appears to be a perfect circle.

On Japan's Tashirojima Island, cats are king.

An immersive environment that is part haunted house, part choose-your-own-adventure, and part jungle gym.

Amid the bustle and noise of the Financial District hides a secluded garden oasis above the city streets.

Rippling sand dunes frozen in the Arizona rock.

America's most famous museum of medical oddities is home to the remains of Albert Einstein's brain.

Most-visited and most-photographed slot canyon in the American Southwest.

A crumbling hospital from the 1850s on Roosevelt Island.

A kaleidoscopic warehouse-maze of handmade neon signs.

World's first "penitentiary," meant to be humane, drove men insane.

A collision of human error and natural geothermal pressure created this rainbow-colored geologic wonder.

One of the few remaining casualties of the London Blitz, this destroyed church has become an enchanting public garden.

A peculiar mansion built by the troubled heir to the Winchester Rifle Company fortune.

This iconic L.A. bookshop is housed in an abandoned bank—both symbolic and chic.

Non-profit time travel mart sells goods you would need for a trip through the fourth dimension.

This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.

World's largest collection of serial killer artwork and other macabre exhibits.

La Monte Young and Marian Zazeela's "Dream House" will immerse you in an ever changing world of sound and light.

A terrific purveyor of natural history objects and curios.