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

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

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

A cavernous three-story, 43,800-square-foot basement that was forgotten about for 60 years.

Before Nixon, "watergate" meant canals.

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

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

This bug-eyed water wheel uses the power of the Sun to clean up Baltimore Harbor.

An out-of-place Air Force radar dome is all that denotes this park as a former missile launch site.

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

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

The bridge's highly-contested plaque (once again) honors Confederate President Jefferson Davis.

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

The oldest continuously operating fish market in the United States.

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

This isn't your average roadway—it's actually a National Park and a transportation pioneer.

A former major munitions plant that has been converted into a sprawling art space.

This brick-lined pedestrian walkway was once a railway tunnel used during the Civil War.

This rare triple-jurisdiction drawbridge passes through Virginia, Maryland, and Washington, D.C.

America's first federal monument.

"Not too many people can say they've had a nuclear bomb dropped on them, not too many would want to." — Walter Gregg.

An unusual, super-sized grocery adventure awaits in an Ohio suburb.

This recently rediscovered Civil War-era submarine was the first to ever sink an enemy ship.

Garden dedicated to native carnivorous plants and site of huge flytrap heist.