A bas relief commemorates the "Nuns of the Battlefield" who cared for soldiers on both sides of the conflict.

Helen Keller once broke ground on this historic center for the study of technologies to benefit the hearing impaired.

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

Before Nixon, "watergate" meant canals.

This forgotten boat elevator was an engineering marvel in its heyday.

The only National Monument ever to go missing for nearly 50 years then resurface in a dump.

Architecture lovers won’t stop touching the National Gallery's 19.5 degree marble prow.

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

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

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

"Congress may voluntarily remain in session throughout the summer, in order that our Congressmen may be protected from the intolerable discomforts and dangers of the ordinary outdoor weather!”

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

A building shaped like the Army Corps of Engineers logo, because why not?

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

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.

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

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

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

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

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

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

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.