All that remains of one of the Civil War's more deadly POW camps is a simple flagstone.

A towering cemetery monument honors a man who threatened to expose the Freemasons and paid with his life.

Mysterious rocks that ring musically when struck.

Dilapidated ruins that once treated a notorious young serial killer, currently hosting vandals, squatters, and ghost hunters.

A girls' boarding school inspired by the Chicago World's Fair, once abandoned, now restored to strange and scenic glory.

This former tuberculosis research hospital endeavored to cure the dreaded disease with fresh air and positive attitudes.

Former farm staffed by mental patients is now a public park.

This notorious Canadian mental institution was home to some of the first LSD experiments and origin of the word "psychedelic."

A long abandoned hospital building on the outskirts of NYC.

The haunting, dilapidated remains of a former poorhouse on Staten Island's Greenbelt.

This hospital fell into ruins after failing to act as the advocate for the mentally ill it was designed to be.

A particularly creepy abandoned hospital that sparks interest for lovers of the supernatural.

Filled with goldfish swimming in a shallow pool of sea water, this ancient crypt is more wishing well than burial site.

Abandoned city hidden from the world by tropical forest and isolation on the coast of Kenya.

An ancient capital city that dates back 3,000 years old and harbors many surprises.

This famous city eluded concrete detection until the early 2000's.

The once great capital of Egypt now crumbles forward as evocative ruins.

A battle between nature and architecture in the Cambodian jungle.

A minotaur, a labyrinth, and a dubious restoration pull in visitors from around the world.

The West's first incursion into the Afghan world lies buried beneath a military base.

Thanks to the building of a life-giving reservoir, part of the Great Wall of China is now a dive site.

A burnt-out motel with priceless Native American artwork in the basement, redeveloped into apartments.

Egyptian treasure trove of fossils documenting the whale's transition from land mammal to sea creature.

The world's second-largest excavated hole.