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

This little brick tunnel built by Confederate forces was used to conduct surprise attacks on the railroad.

An original apothecary from 1792.

The final resting place of an unidentified revolutionary soldier sits behind a Virginia church.

A massive, majestic mammal watches over pedestrians from his perch atop a former B.P.O.E. lodge.

An abandoned railroad tunnel transformed into a creepy path for hikers and cyclists.

Once a sewer culvert, this road tunnel now offers cyclists and pedestrians a subterranean stroll under the C&O Canal.

A well-preserved relic of the industrial age steel and iron works that dotted West Virginia.

Two gems of Beaux Arts architecture that have been sitting vacant for years.

This university transit system is a 1970's vision of the future.

The oldest continuously-operating tavern in Wisconsin used a clever loophole to serve alcohol during Prohibition.

This road in the Great Smoky Mountains was supposed to assuage a displaced community, but ended up a $52 million dead end.

Hidden behind a gate in Greenwich Village is a little farmhouse that once served as the writing studio of a bestselling author.

This 170-year-old Swiss guesthouse built into the side of a mountain is best accessed by a cable car.

The remains of the iconic train crash from the movie The Fugitive can still be found rusting along the Great Smoky Railroad.

The largest cemetery for enslaved people in Loudoun County was almost lost to history, if not for the research of a minister.

Under a glass sidewalk lie the remains of some of Manhattan's oldest buildings.

In a dry, neglected cemetery lies the unassuming grave of a soldier vilified in life but celebrated in death.

Monty Python fans will recognize this abandoned mine as the Cave of the Killer Rabbit of Caerbannog.

Recognized the world over as the home of the McCallisters in the 1990 movie "Home Alone."

A circle of giant painted vases in the former pottery capital of the United States.

A lovely aquatic park built by a one-armed Civil War veteran who made a fortune from lotuses.

This giant boulder is sandwiched between apartment complexes in upper Manhattan.

The hill that gave the Massachusett tribe, and later the state, its name.