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

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

Locals call this magical moss-covered walkway the "Emerald Path."

Erected in 1697 this Philadelphia bridge is the oldest surviving roadway bridge and perhaps the oldest stone bridge in the United States.

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

The only geyser in the state of Pennsylvania is caused by pressure from an abandoned coal mine outside of the ghost town Centralia.

The pop art icon's gravesite is broadcast 24 hours a day on his museum's website.

A local prank turned town icon.

The home and studio of a visionary woodworker now stands as a museum and example of his artistic genius.

Journey through a collection of over 35,000 Halloween items from all generations.

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

Pennsylvanian mass grave and possibly mass murder.

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

This eccentric mansion museum holds a impressive collection of rare and automatic instruments.

An outlandish shoe shaped house built by an eccentric millionaire.

Pennsylvania's own Roswell-style UFO mystery.

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

An 18th-century Catholic church converted into an eccentric temple of music and bacchanalia.

Its vintage camera collection gives a snapshot of the past as viewed through a photographic lens.

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

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

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

A historic covered bridge is but one example of an oddly prevalent American urban legend.

The largest university building in the West is a gothic masterpiece containing dozens of theme rooms based on different countries.