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

A cavernous three-story, 43,800-square-foot basement that was forgotten about for 60 years.

An atomic bomb-proof strongbox protects the U.S. Constitution from terrorists and thieves.

There’s a hidden military meme engraved on the World War II Memorial.

A nostalgic bibliographic gem.

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

Home to items never before seen by the public.

Atop this media building, two hives containing more than 30,000 bees keep the surrounding area vibrant.

This stunning blue and gold room changed cities twice before becoming part of the Smithsonian.

This sandwich shop has a century-old elevator behind a sheet of plexiglass.

There's a 12-foot-tall replica of the Washington Monument hidden under a manhole nearby.

America's Most Wanted's set resides in this tribute to the history of crime and punishment.

This Philly cemetery is the eternal home of many famous area residents, including Rocky Balboa's wife.

The first American department store, and home to the largest operating musical instrument in the world.

The haunting "Hell House Altar" is one of the few remnants of an abandoned college that has been a magnet for local legends.

The world's second-longest burning light bulb.

Three hundred years of preserved Spanish colonial history in San Antonio.

The only place to see live frogs don pigtails and top hats, then eat their scrumptious legs.

An ivy-covered arch bridge dedicated to Tejano music singer and legend Rosita Fernandez.

A master plumber has turned his love of art and toilets into a folk museum that's not taking the piss.

These boots are made for selfies.

A decaying concrete oil tanker served as a disposal location for bootleg hootch.

An enormous pink granite batholith, long attributed with spiritual powers by the Tonkawa Indians.

The peaceful space is adorned by paintings by the famed abstract artist Mark Rothko.