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

A crumbling hospital from the 1850s on Roosevelt Island.

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

Rippling sand dunes frozen in the Arizona rock.

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

An artsy hidden staircase leads to breathtaking views of San Francisco.

A psychedelic labyrinth on the San Francisco bay.

A terrific purveyor of natural history objects and curios.

A huge musical instrument played by the ocean.

The wartime prison now features haunting sculpted reenactments of the atrocities that took place there.

An extravagant monument to an extravagantly unpopular Emperor.

This spectacular bridge supported by two gigantic hands looks like something out of a fantasy universe.

World's largest cave was only discovered in 1991, and now offers tours to the public.

Khmer Rouge's high security prison.

A battle between nature and architecture in the Cambodian jungle.

A former French military respite turned jungle tourism hotspot.

The world's first cruise ship-shaped hotel is perched atop a cliff.

Along a rail-biking route, giant insects house a two-story restaurant.

Asia's largest limestone cave is home to a world of plastic goblins and gold mining history.

A chilling monument to Korean patriots who resisted the Japanese occupation.

To enter the lower hall of this temple, you must first walk through a dragon.

South Korea's only sex-themed park.

Secret North Korean passage discovered below the world's most dangerous border.

The abandoned hospital whose elaborate ghost stories cover up the dirty truth - an uneventful sanitation issue and other mundane reasons for its demise.