Under a playground is a little-known sealed train tunnel that likely contains the bodies of workers trapped by cave-ins.

This 29-ton granite ball spins around at the slightest touch thanks to a scientific phenomenon.

A small Richmond island dotted with the remnants of hundreds of years of history.

Heron, whitewater rapids, and urban industrialism all add to the beauty of this concrete nature walk.

A relic of FDR's brief foray into utopian urban planning.

A mammoth pair of Civil War artillery guns abandoned out in the forest.

Remains of a historic fountain that was mysteriously lost in the demolition of a D.C. traffic circle.

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

Unicorns, elephants, and bears, oh my!

The remains of a historic plantation nestled in between a parking lot and the rental car return at Reagan National Airport.

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

These unusual rooms on wheels are holdovers from the 1960s.

The semi-reclaimed ruins of this canal were once part of an ambitious plan to reroute the mighty potomac.

The final resting place of the tragic king and queen of the Jazz Age is tucked away in a small Maryland graveyard.

A suburban museum tells the story of a historic transportation network and even provides rides in antique trolley cars.

The longest escalator in the Western Hemisphere takes over three minutes to ride down.

Live data is transmitted from the Atlantic coast to instantly recreate the ocean waves in this fountain at the NOAA headquarters.

Giant acorn-shaped 19th century gazebo from which suburban Washingtonians gazed upon the original "silver" spring.

The rooster who crossed the road lives on forever in Takoma Park, Maryland.

A tiny piece of the Moon is embedded in this stained glass masterpiece.

A Civil War fort in the middle of Washington, D.C. has been swallowed by a forest.

Behind an abandoned storefront is an example of pioneering 1930s gas station architecture.

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.