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

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

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

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

Washington's top-secret Cold War-era doomsday communications tower is located in a small neighborhood park.

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

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

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

Go take a picture with the inventor of the daguerreotype photographic process.

The only Civil War battle in Washington D.C. took place near this highest natural point in the city.

A gorgeous mural outside a beloved D.C. restaurant pays homage to famous Black Americans.

A traveling postal dog covered 48 states and more than 140,000 miles, and he lives on as taxidermy, patched up with a rabbit's foot and a pig's ear.

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

Washington's iconic carousel has a nice piece of Civil Rights history.

The unique traffic pattern named for an influential urban planner is also known as the Pedestrian Scramble.

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

The most accurate timepiece in the world.

A haunting tribute to pioneering photographer Clover Adams.

Obscure Freemasons still live in D.C.’s largest private residence.

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

There’s a hidden military meme engraved on the World War II Memorial.

A derelict bit of transportation infrastructure hidden in the woods.