A bit of retro transportation flair preserved in the world's largest department store.

Hidden in an ordinary Midtown building is a one-room museum dedicated to the greatest escape artist.

Rebuilt remains of a temple to Roman god Mithras.

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

A crumbling hospital from the 1850s on Roosevelt Island.

A terrific purveyor of natural history objects and curios.

A beautiful and abandoned New York subway station from 1904, complete with chandelier.

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

An abandoned hotel in the highlands of Bali is shrouded in stories of ghosts, curses, and corruption.

One of the most important yet well-hidden museums dedicated to the history of medicine.

The secret room where early Bolsheviks cranked out propaganda fliers on a smuggled printing press.

"There's nothing there," and other lies the KGB told us.

A simple plaque on the facade is the only reminder that the treaty ending the American Revolution was signed inside.

The largest medical and anatomical collection in France lies hidden from the public.

Named after a militant urban guerilla, this famous former squat is a graffiti-covered stronghold of leftist culture.

This off-limits room in the National Library of France is home to a system of pneumatic tubes, once used to bring books to readers.

A quiet, gothic haven nestled between Pittsburgh's Squirrel Hill and Point Breeze neighborhoods.

A Lycian city of the dead carved into the hillside of Southern Turkey, complete with startlingly human touches.

Rock-cut caves and 7,000 Buddhist sculptures carved into the nearly sheer face of a sandstone mountain.

A winding path built in secret on the edge of the continent.

This shop specializes in oddities and Victorian-inspired wonders.

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

A 140-year-old castle with underground caves hidden in San Francisco.

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