A computer bug so primitive it was an actual insect.

When it opened during the final years of the embargo, all the drinks and cigars were free.

The actual model from the original "Star Trek" series is now on display at the National Air and Space Museum.

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

People escaping slavery may have hidden inside a corpse vault.

The most decorated dog of World War I is preserved in the Smithsonian.

The walls of the iconic dome are hollow and have a secret stairway.

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.

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

A wondrous old library overlooking the nation's capital.

A historic neighborhood church is reborn as a psychedelic arts collective.

Franciscan monks created a facsimile of the Holy Land for North Americans who couldn’t afford the trip overseas.

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

A monument in Washington D.C. marks the spot from which all other roads were supposed to stem.

Enormous piles of historically significant stones, dumped by Congress in a forest, and abandoned for 60 years.

One of the dwarven trees dates back to 1625 and survived the Hiroshima bombing.

Long-abandoned trolley tunnels just a mile away from the White House are turning into an art space.

With over 100 jam-packed rooms to explore plus elaborate tea services and events, the Mansion on O Street is a hidden treasure.

This bright yellow relic is the final survivor of a short burst of seashell-shaped petrol pumps.

The final resting place of the hundreds of bodies originally buried where Badin Lake sits now.

This ceremonial mound is one of the first officially recognized Native American historical sites in North Carolina.

Jule Körner's house full of bizarre architectural details.

A six-foot pair of socks hangs from a drawer of the world's largest bureau.