Dug as a secret royal escape route, the tunnel became a wartime bomb shelter and dumping ground for vintage cars.

These "anatomical machines" are only one of the many strange items in this Italian crypt.

A labyrinth of ancient tunnels hidden below the city holds the ruins of 2,500 years of history.

The once forbidden "secret cabinet" of erotic art from excavations of Pompeii and Herculaneum.

Like something out of a bad acid trip, this Ukraine hallway has been covered in hallucinatory phantasmagoria.

No one is sure if the world's fourth-largest diamond had been found in a rubbish heap or was pawned by Napoleon's mom.

This crucial gathering spot along the "hippie trail" still displays old notes between traveling beatniks and backpackers.

This eatery re-creates dishes from the Ottoman Empire so you can dine like a sultan.

Step back in time and witness the fall of Constantinople.

Legend says if you stick your thumb in the hole and it gets wet your wish will be granted.

An outdoor urban gallery of large-scale artworks by the world's most influential street artists.

These pretty kitties killed and ate as many as 135 railway workers.

A little-known subterranean street runs under some of the best-known buildings in Chicago's River North.

A display of magnificent stained glass windows is the first exhibit of its kind.

A science teacher's dream.

The subtle science of a master molecular gastronomist.

A bloodstain from "the wound of the transverberation of the heart."

This surprising gem is a world-class archeological museum hidden at the University of Chicago.

Home to a protest movement, a bombing, and a dramatic change in labor history.

The unluckiest U-boat in the entire German fleet is now on display in a Chicago museum.

The beloved home to all publications indie, erotic, and punky.

Fragments of architectural wonders from around the globe are embedded in the newspaper building's walls.

A shining sculpture made of 3,115 lights, the number of visible stars in the Northern Hemisphere.

The world's only known button museum.