A clone-tree in Washington Square Park sprung from seeds that went to the Moon and back.

A mine fire has been burning under the deserted town since 1962, but this church is still going strong.

Dr Barnes' $25 billion private collection of art and arboretum.

In which a local geological marvel becomes a quaint roadside attraction.

Over 100 concrete munitions bunkers are all that remain of a Pennsylvanian village seized by the US government.

This eerily well-preserved coal town was saved from destruction by a Sean Connery movie.

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

A park full of outsider art, created by college students studying outsider art.

Mutant vegetables, transgenic mosquitos, and atomic rodents span the walls of this one-of-a-kind museum.

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

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

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

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

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

"Dark Sky Park" is heaven on Earth for astronomers, one of the rare U.S. locations with no artificial light pollution.

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

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

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

Mysterious rocks that ring musically when struck.

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.

A toxic ghost town sitting atop a massive coal fire.

World's first "penitentiary," meant to be humane, drove men insane.