Secret Passages

A 19th-century house filled with secret trap doors and hidden basements has been turned into a museum.

Use a key to unlock this medieval sewer tunnel.

The eccentric midcentury home of a suspected mafia gun-runner.

The enormous 250-room Vanderbilt mansion conceals hidden doors and secret passageways.

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

The winding route passes through an enclosed alleyway, two tunnels, and leads to the White House basement.

The nearly 200-year-old folly has a secret spiral staircase hidden in one of its pillars.

Illegal drag racing two stories beneath Chicago’s streets.

The tunnel under the Capitol Building where Congress takes out its trash.

A room hidden behind a swinging shelf in the children's section.

Daredevil repair workers can worm their way out the access hatch, loop ropes over the apex and rappel down the monument.

A painfully obvious spy house sits right across the street from the Russian Embassy.

The first presidential bomb shelter was located in an old vault under the Treasury, connected to the White House via tunnel.

A faux European lane smack dab in downtown L.A.

Hidden behind Lincoln's head is a 70-foot-long chamber containing enamel plates documenting American history, sealed in a teakwood box in a titanium vault.

The doodles of a genius line the walls of a secret room under the Medici Chapel, where they were hidden for nearly 500 years.