Mysterious rocks that ring musically when struck.

Dedicated to one of the most successful boxers to compete in the heavyweight division.

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

In use from 1742 to 1910, only flat headstones were allowed in this cemetery.

George Washington, Alexander Hamilton, and Benjamin Franklin all slept at this humble inn.

One of the world's oldest continually operating bookstores.

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

One of the first commercially successful anthracite-powered iron-making operations in North America.

A smaller model of the Da Vinci sculpture that took 500 years to come to life.

A "house to which to flee" for settlers in colonial Pennsylvania.

America's oldest drive-in movie theater has been in continuous operation since 1934.

Designed by the company that provided water to the entire community.

The famous bell was secreted away and hidden in a church in Allentown during the British occupation of Philadelphia.

A fascinating community art piece created by students, teachers, and noted Philadelphia artist Isaiah Zagar.