The span is crooked and made from two older recycled bridges.

A public art jibe at one of the United States’ oldest and longest-serving senators.

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

A historic cemetery with unique artwork, a Civil War fort, and also happens to be the site of the Battle of Bladensburg.

A super-sized promotional trick that is now a D.C. landmark.

An overlooked oasis of quiet on the grounds of Washington's monumental basilica.

A giant time capsule not scheduled to be cored until 2040.

A monument marks the location of the first successful steamboat demonstration.

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

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

The iconic D.C. restaurant where the Cuban Missile Crisis was negotiated, now a Walgreens.

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

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

Before Nixon, "watergate" meant canals.

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

Thousands of tiny squares in different colors make up this piece of street art.

This robust fence in front of a historic Georgetown home is likely made from hundreds of recycled Revolutionary War firearms.

An unusual sculpture, an interesting history, in a strange place, for a good cause.

An intricately designed junk art house with four extravagant junk art cars hidden in the suburbs.

A surprising, but overlooked example of geology in the middle of the nation’s capital.

A tribute to the beloved, kind-hearted "homeless mayor" of Silver Spring.

A historic ruin just 20 feet away from a busy highway onramp.

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

At 207 feet, one of the world's longest continuous escalators.