These abandoned waterworks are crumbling into the Potomac River.

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

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

The preamble to the U.S. Constitution written entirely from vanity license plates hangs in the Smithsonian museum.

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

A derelict bit of infrastructure from the canal that once ran through D.C. is landlocked in the heart of the city.

A muscular Art Deco monument represents the struggle between regulators and unbridled markets.

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

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

An overlooked memorial honoring the local Washington residents who died in World War I.

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

Need a hardcopy of the 50-title Code of Federal Regulations? This is the place.

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

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

This seemingly out-of-place gas station by the Watergate hotel was once described as the most expensive gas station in the world.

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

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

One of the most influential presidents in U.S. history wanted only this plain, elegant monument as his lasting memorial.

The school tested mustard gas for the U.S. Army during World War I.

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

A museum cafe showcases Native American dishes and indigenous ingredients from across the Western Hemisphere.

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

While most wind tunnels test scale models, the "Cave of Winds" was large enough for actual airplanes.

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