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

A beloved horticultural oasis on the grounds of a wealthy family's former estate.

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

The slate extracted from these Pennsylvania quarries was once hailed as the finest in the world.

This roadside stand packs 300-plus varieties of tomatoes, from "Maiden's Fire" to "Kaleidoscopic Jewel."

Pennsylvania's highest point is spotted with boulders which were pushed to the surface by nothing but cold.

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

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

This semi-spooky remnant of an abandoned hotel provides fantastic views.

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

Instruments, apparatus, and rare books all relating to chemistry and its related sciences.

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

This Philly landmark has a giant butterfly pavilion, three floors of insect displays, and withstood a $40,000 heist.

The residents of the Neighborhood of Make-Believe live without much fanfare within the Pittsburgh Children's Museum.

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

The internal railway of one of the biggest steel plants in America has been transformed into a linear park with unique industrial views.

This hidden gem of a garden has one of the only surviving Victorian ferneries in America.

This might just be the TARDIS of bookstores.

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

The oldest surviving botanic garden in the United States.

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

This little-known collection holds everything from "Dracula" notes, to the manuscript of "Ulysses," to the forged works of Shakespeare.

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

Sail through this subterranean show cave that is home to a legend that would go on to name nearly everything around it.