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

A 1,100-ton train fell through the floor in 1953. Workers got it patched up in just 72 hours.

This restaurant has been a haven for D.C.'s LGBTQ community since the 1950s.

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

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

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

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

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

Look closely and you’ll notice that the color changes a third of the way up the tower.

The little-known, 300-year history of the area includes former lives as a bustling tobacco port, parking lot, and industrial dump.

Art deco landmark on the outskirts of Washington, D.C.

One of the largest artillery pieces in the world sits in a Washington D.C. parking lot.

Legend has it that President Grant’s frequent drinking in the lobby gave rise to the term “lobbyist.”

Those with a sharp eye can find the hidden image of a German Shepherd on the memorial's Mural Wall.

A little marble compass above George Washington's (empty) tomb in the Capitol marks where D.C.'s four quadrants intersect.

Members of Congress have traveled between the buildings on Capitol Hill for a century hidden from tourists, press, and storm clouds.

The remains of Martha, the last known passenger pigeon, serve as a tool to educate about conservation.

The "lovely red Vega" of the legendary record-settling pilot.

Decades before the scandal, this staircase on the river was a literal "water gate."

The oldest building in the District of Columbia was preserved because of a mistaken connection to George Washington.

There's a crumbling old mansion inside the Smithsonian National Zoo.

The house where John Wilkes Booth conspired with his co-conspirators.

The oldest continuously operating fish market in the United States.

The first purpose-built art gallery in the United States is once again open as a center of craft arts.