A cave on the Maryland border where civilians took refuge during the bloodiest battle of the Civil War.

The last of nine massive kilns that produced many of the red bricks for buildings in Washington, D.C. and northern Virginia in the early 20th century.

This restored house built from a Sears kit in the 1930s is a physical remnant of FDR's New Deal following the Great Depression.

This former Cold War missile control site played an important role in the creation of GPS.

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

Three abandoned missile silos are hiding in plain sight behind a suburban development in Maryland.

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

The shelves in the back of this thrift store are devoted to saving, not selling, retro tech.

An intricately designed junk art house with four extravagant junk art cars hidden in the suburbs.

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

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.

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

This grave marks the passing of a historic Jane Doe whose identity remains a mystery to this day.

This might just be the TARDIS of bookstores.

Mural made of 100,000 pieces of hand blown glass, and until recently, the largest glass mural in the US.

The oldest family-run luncheonette in New York, last renovated in 1948, still serves food and drinks the old-fashioned way.

Giftshop catering to cryptozoologists and anyone with a sense of humor.

Two dozen pinball games hidden away inside a most unlikely location.