The United States Capitol's former columns still stand.

Rumored to be the famed pirate's lookout tower, this historic stone structure is now just watching for tourists.

One of the oldest of its kind.

This elaborate towering structure was once famed for its revolutionary height.

The site of the climactic scene from the classic horror film is now a historic landmark.

Parking garage where Bob Woodward met Watergate source "Deep Throat."

Rediscovered after a century, the father of the American Navy was reinterred in something dredged up from Davy Jones' Locker.

This fort down the Potomac from Washington, D.C. was once the only defensive fort protecting the capital.

Once home to seven different roller coasters, Glen Echo has undergone many transformations since its founding in 1891.

The ruins of this long-abandoned unsuccessful gold mine can still be found.

Part of a WWII submarine is lurking outside the Washington Navy Yard parking lot.

This lovely picnic spot featuring thunderous jet landings is an aircraft spotter’s dream.

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

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

One critic described it as "middle Mussolini, early Ramses, and late Neiman-Marcus." Another called it an architectural "natural disaster."

The elevator that makes it possible to fly American flags in bulk over the U.S. Capitol

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

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

The national park was once a plantation estate.

A hoard of sky catalogs, astrophysical journals, even the works of Galileo and Copernicus.

A celebrity from the late Cretaceous period.

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

The most accurate timepiece in the world.

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