This abandoned sea fort has become an accidental bird sanctuary.

A secretive collection featuring objects that were designed specifically for U.S. intelligence operations.

This pre-Revolutionary War grist mill ground corn and flour for soldiers in seven American wars.

This abandoned asylum was once a state of the art facility before devolving into one of the most deadly mental institutions in American history.

A girls' boarding school inspired by the Chicago World's Fair, once abandoned, now restored to strange and scenic glory.

Fascinating museum dedicated to the under-appreciated medical history of urology features some wince-inducing devices.

A hidden alley in urban Baltimore is a haven for graffiti artists.

The haunting "Hell House Altar" is one of the few remnants of an abandoned college that has been a magnet for local legends.

Crammed into a Baltimore row house is an oddities shop that sells everything from skulls to dead insects.

The famous bell was secreted away and hidden in a church in Allentown during the British occupation of Philadelphia.

Walk a trail through a historic Quaker town that outlawed slavery in 1777 and was a major waypoint on the Underground Railroad.

These beautiful ruins deep in the Pennsylvania woods are thought to have been a ski lodge or a speakeasy, but no one really knows.

Remnants of a storybook amusement park hidden behind a strip mall.

Conveniently located within binocular range of a nuclear bunker, the "summer camp" area was a painfully obvious spy house.

A failed piece of Orientalism has become the proud symbol of a community.

This jail which was in service for over a century is now open for curious visitors.

A memorial to the 1913 tragedy that helped protect the workers of the future.

A gazebo that inspired the fifth episode of the "Twilight Zone" still stands in the creator's hometown

The first of Lancaster's "rural cemeteries."

The oldest farmer's market in America is so ancient it was approved by the King of England.

The Home and murder site of the witch of Rehmeyers Hollow.

Buildings that dynamite couldn't bring down were abandoned because of bathroom issues.

A historic home with ties to the abolition and suffrage movements.

A Civil War Museum with some notable medical antiques.