What looks like a simple quaint estate in rural Pennsylvania was in the 18th century home to a small monastic community.

Steepest flood safety railway in the entire world.

The last street in Pittsburgh that's paved with wood.

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

Pennsylvania's own Roswell-style UFO mystery.

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

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

This lab's maddening silence is good for business but bad for sanity.

This massive airship factory is so large that it has its own indoor weather.

The brainchild of Eleanor Roosevelt, her "Little Village" was a collectivist dream.

10,500 square feet of pinball housed in former dollar store and home to the last playable "Thunderball."

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

Sections of the iconic limestone columns have been left uncleaned as a reminder of the city's polluted past.

This elaborate towering structure was once famed for its revolutionary height.