This ruined fort hidden at the top of Central Park can't seem to keep from losing its historical plaques.

The oldest operating apothecary in the US has treated everyone from Thomas Edison to Mark Twain.

An abandoned castle owned and ignored by Masons carries a cursed history.

A tunnel once abandoned now thrives with graffiti art as an off-limits makeshift gallery.

A stunning, two-tiered waterfall made famous by poets, artists and the legend of a ghost dog.

Elevated freight railway turned wildly successful urban park.

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

Beautiful views of the surrounding hills and birds of prey can be found at this sanctuary.

Visitors to Salt Springs State Park are encouraged to literally put their two cents in Penny Rock.

This historic furnace was once used to produce cannonballs during the Civil War.

The site of the little-known Pennsylvania battle that sparked the Seven Years' War.

A hidden piece of Altoona's railroad history in a long-forgotten abandoned town.

Contrary to what one might expect, ice forms inside this small cavern during the summer and melts during the winter.

Behold the rickety wooden glory of the world's oldest operating roller coaster.

This secluded walking trail is a hidden gem of a Pittsburgh park.

This huge, disused viaduct is now a crumbling concrete underworld of covered in years of graffiti.

This Pennsylvania cave holds evidence of the oldest known inhabitants of North America.

Pennsylvanian mass grave and possibly mass murder.

It would take 35 firetrucks to fill this enormous glacial pothole.

The ruined remains of a coal mining ghost town are hidden within the woods.

When the Austin Dam failed it destroyed much of Austin...and then it failed again.

The graffitied ruins stand hidden within the Pennsylvania woods.

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

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