A sacred collection of indigenous rock art.

A museum dedicated to the history of electric interurban transit near the home of the first electric trolley system in the United States.

A converted hangar displays dozens of helicopters, from a famous 1943 rescue chopper to several autogyros.

An underground blaze turned this village into a ghost town.

Grand architectural relics gain a new life in this Pennsylvania warehouse.

Construction uncovered this trove of fossils, which visitors are welcome to add to their own collections.

A comprehensive collection of toy and model trains, largely from the mid-20th century.

The lasting remains of the region's once booming cement industry.

One of the world's oldest continually operating bookstores.

The first marker along the famous boundary.

A wonderous place devoted to art and metal.

One of the oldest surviving lock houses on the Ohio River.

This quarter-mile tunnel under the Bluff in Pittsburgh bends at a 45-degree angle.

Catch a ride through the Pennsylvania countryside on this historic narrow-gauge railroad.

A small granite block at this monument's base is the only part of Lincoln's Tomb outside of Illinois.

Surrounded by industrial sprawl, a small monument marks the site of William Penn's first landing in Pennsylvania.

The meeting of the northwestern corner of Delaware, the northeastern corner of Maryland, and the southern edge of Pennsylvania.

When oil was discovered just outside of Pittsburgh, the city became home to this regional stock market.

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

A bronze statue of Mister Rogers in the neighborhood where he grew up.

These hooded graves are the only of their kind in the United States.

Overshadowed by quilts, the artistry of these patterned textiles went underappreciated for too long.

This 15-foot tall obelisk commemorating the Philadelphia-Baltimore railroad connection sat neglected for over a century.

These unique rock formations were created during the Ice Age.