Pittsburgh's literal underground railroad.

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

One man's real life disfigurement inspired a lasting local legend surrounding an eerie tunnel.

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

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

This icon of the Atomic Age now lays dormant.

A museum commemorating the Donora Smog, which killed 20 people in October 1948 and sparked national outrage over air pollution.

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

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

A macabre farm reserved part of its 222-acres for dead bodies, all in the name of science.

Despite violent work crews and massive delays this abandoned canal tunnel was built to last into the modern day.

A remarkable time capsule of American manufacturing deep in Maryland coal country.

Penn State's giant bug collection.

The universally beloved children's television figure is interred on a high hilltop in one of western Pennsylvania's oldest cemeteries.

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

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

Memorializing an American tragedy of massive proportions.

It marks the spooky spot where the bodies of two young boys were found in the 19th century.

The mortal remains of a Russian prince, priest and paranormal investigator who came to America in 1792.

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

Long hidden under grime, the politically radical murals of a little known Yugoslavian master are finally getting their due.

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