Try not to get slimed in Tribeca.

The unique waterfall in Iceland's south features a backdrop of geometric black lava columns.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

The only structure left with direct ties to the Salem witchcraft trials of 1692.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

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

Dramatic river bend surrounds a natural red-rocked pedestal.

The sign at the garden gate reads: "These Plants Can Kill."

Medicinal spa created with the discharge from a geothermal energy plant.

The intricate stonework of Machu Picchu serves as a testament to Incan engineers.

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

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

Rippling sand dunes frozen in the Arizona rock.

The macabre collection of Jacques Sirgent, an expert scholar on the undead and all of their trappings.

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

The highest peak in the United Kingdom has a history of physics, specters, and a pilgrimage of strange objects.

No telescopes, no power, no gift shop: The Observatory of Chichen Itza, one of the world's oldest observatories, takes astronomy back to basics.

This tiny, painted door at the base of a tree stump has been a fixture of the Harvard University campus for decades.

The most powerful waterfall in all of Europe.

The gravestone of the suffragist leader attracted extra visitors during the 2016 election.

A brisk climb up this solitary peak leads to the origin story of a towering figure in Irish history.

This Virginia town has been famous for its fried chicken since the 19th century.

Giant origami sculptures tucked into desert scenery beckon passers-by to explore further.

The mysterious wonder of an underground waterfall is illuminated by multicolored lights.