A street in front of NASA's D.C. headquarters has been named in honor of the Black women who were essential to early spaceflight.

The only Leonardo Da Vinci painting in the Western Hemisphere.

Railroad officials in the early 1900s sought to spare travelers the sight of Roman soldiers’ private parts.

The only tennis court that falls under the jurisdiction of the central bank.

One critic described it as "middle Mussolini, early Ramses, and late Neiman-Marcus." Another called it an architectural "natural disaster."

Outside the Department of Transportation, a collection of artifacts honors the history of how we get around.

The legacy of a wealthy executive and his wife, this little-known art museum features works by Picasso, Monet, Renoir, Cezanne, and more.

An overlooked tribute to one of the most important peace deals in American history.

The 5.5-mile ring of steel posts around the Capitol Building is one of the largest (and most uniform) of its kind in the world.

This statue of the "father of television" stands prominently in the United States Capitol.

The tunnel under the Capitol Building where Congress takes out its trash.

The story behind this beloved toy—named for Theodore Roosevelt and owned by his grandson—is more complicated than you might guess.

Disks are rolled out onto the south lawn to absorb the impact of Marine One's wheels like giant coffee coasters.

An echo chamber with a waterfall wrapped around its base at the Embassy of Canada in Washington, D.C.

An amazing example of early-20th-century architecture, this church features marble transported from Utah.

Garments from across the globe call this hidden gem home.

Depending on who you ask, this controversial treehouse is either a charmingly creative child's playhouse or an illegal encroachment on public land.

A memorial to a shareholder activist feared by CEOs around the United States.

After his presidency, George Washington planned to live only a few blocks from the Capitol building.

The grand marble structure next to the White House is Andrew Carnegie's temple to Pan-American diplomacy.

A replica of the famous memorial statue at the Normandy American Cemetery hides in an office building in downtown D.C.

Coins and medals straight from the mint await visitors to this shop in the nation's capital.

An ear-piercing buzzer calls lawmakers to a vote with a series of long and short rings to form coded messages.

D.C. once had its own tiny rival to the New York Stock Exchange.