These disused steel furnaces are now haunting ruins that may one day be a national park.

A quiet, gothic haven nestled between Pittsburgh's Squirrel Hill and Point Breeze neighborhoods.

The Pennsylvania landscape depicted by a quarter mile of mosaics made from used road signs.

The remains of a community that was forced to move for a dam that never materialized still rot in this Pennsylvania park.

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

A train station that was abandoned by the coal industry and was later converted into a cocktail bar.

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

Once the "Eighth Wonder of the World," this iron railroad bridge was decimated by a tornado.

This abandoned Poconos resort is haunted by a history of kitschy romance and a violent fugitive.

This might just be the TARDIS of bookstores.

One artist's love letter to his city and its citizens plays out across dozens of bright murals painted on the sides of decrepit buildings.

Collection of trolley cars in the woods represent one man's attempt to preserve transportation history.

This charming colonial alleyway is one of the oldest continuously used residential streets in the U.S.

A modern ghost town whose inhabitants were driven away by the growth of nuclear power.

A stone arch leads to a cavernous 1930s spring house tucked away in the Pennsylvania woods.

One of the steepest streets in the United States makes an intriguing challenge for cyclists.

Eccentric concrete mansion and museum designed and built by hand from the inside out.

Huge masonic hall in Philadelphia with lavishly themed rooms.

Found art has transformed this Pittsburgh neighborhood into a psychedelic dream.

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

An abandoned stretch of highway, deteriorating next to the operational one.

Where America's first doomsday cult awaited the end of the world.

Hellam Township is reputed to feature seven remote gates, which when passed through in the right order, open an entrance to hell.

Mysterious rocks that ring musically when struck.