A small token of gratitude from freezing cold journalists who were given a warm haven while covering JFK's inauguration.

This mysterious structure by the Washington Monument is a flood barrier designed to protect the White House against rising waters.

A portal into the bricked up canal that runs through the heart of Washington D.C.

A hidden passageway now marks the site of an assassination attempt on Ronald Reagan that some say broke a 140-year-old curse.

‘Bush the old fire dog died of poison July 5th, 1869. RIP.’

A promising candidate for the lost rock laid by George Washington was unearthed, but the hunt is still on.

The first memorial dedicated solely to the Black troops who fought for the Union.

Part of a WWII submarine is lurking outside the Washington Navy Yard parking lot.

The elevator that makes it possible to fly American flags in bulk over the U.S. Capitol

Also known as the Founding Church of Scientology.

An obscure federal monument honors the French diplomat who served as Ambassador to the U.S. during WWI.

Before Metro, Washington had a robust streetcar network—and you see the remains of this infrastructure if you know where to look.

The early data processor factory founded in Washington for the 1890 U.S. Census went on to become IBM.

Behind an abandoned storefront is an example of pioneering 1930s gas station architecture.

This nine-story building is the oldest standing skyscraper in D.C.

Was there a small "backpack nuke" hidden in the attic? JFK apparently thought so.

For 60 years, the academy had no permanent location until members voted Washington D.C. as its forever home.

A diminutive memorial marks the site of a successful assassination by a right-wing death squad in America's capital.

During Prohibition, the U.S. Congress had an "official" bootlegger, with his own Capitol Hill office.

The fountains of the U.S. Navy Memorial are annually salted with water from the Seven Seas as part of a nautical ritual.

A tiny monument to the unsuccessful attempt by Thomas Jefferson to place the prime meridian in Washington.

There just so happens to be a court even higher than the U.S Supreme Court: a basketball court in the building itself.

When it comes to handsignals (and colonialism) rock always beats scissors.

This stately mansion, built in 1787 by America's first Secretary of the Navy, is rumored to be one of the most haunted buildings in Washington, DC.