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

A derelict bit of infrastructure from the canal that once ran through D.C. is landlocked in the heart of the city.

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

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

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

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

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

Members of Congress have traveled between the buildings on Capitol Hill for a century hidden from tourists, press, and storm clouds.

A little marble compass above George Washington's (empty) tomb in the Capitol marks where D.C.'s four quadrants intersect.

Decades before the scandal, this staircase on the river was a literal "water gate."

Perhaps the most scandalous statue of America's first president.

D.C.'s first central library was born out of a chance encounter with the philanthropist whose name it bears.

America's first federal monument.

The oldest continuously operating fish market in the United States.

The country's oldest continually-operated mini golf course lies hidden in plain sight, eclipsed by one of D.C.'s most popular tourist attractions.

Fittingly, America's museum of architecture is itself a magnificently designed old building.

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

The preamble to the U.S. Constitution written entirely from vanity license plates hangs in the Smithsonian museum.

On the Fourth of July this area will transform into a Pompeii-like storm of falling embers and ash.

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

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

A line of blue paint marks the route of the inaugural parade.

The bank that helped fund the Mexican-American War and the purchase of Alaska met its downfall after helping Augusto Pinochet launder money.

The beloved statue at the National Academy of Sciences is oh so inviting to sit on.