Edison's cast-in-place concrete houses were a failure, but way ahead of their time.

Now abandoned, the first public health hospital in the U.S. saw more than one million immigrants from around the world.

The first memorial dedicated solely to the Black troops who fought for the Union.

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

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

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

While most wind tunnels test scale models, the "Cave of Winds" was large enough for actual airplanes.

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

This stately mansion, built in 1787 by America's first Secretary of the Navy, is rumored to be one of the most haunted buildings in Washington, DC.

A much-maligned monument to teetotalism.

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

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

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

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

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

An unassuming, powerful monument north of the U.S. Capitol bears witness to the resilience of Japanese Americans during a time of grave injustice.

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.

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.

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.

A celebrity from the late Cretaceous period.

Rumor has it the uncarved lump behind the three famous suffragists is reserved for the first woman president.

This imposing Masonic temple a mile from the White House was the first public library in Washington, D.C.