You've been to all the most popular museums and tourist landmarks in Pennsylvania: Independence Hall, the Carnegie Museum of Natural History, etc... What about some of the lesser-known historical sites? Lord knows Pennsylvania is not lacking in them. Here are 10 hidden gems in Pennsylvania that offer fascinating glimpses into our history.

1. Indian God Rock

In Rockland Township lies an object that has been the subject of significant archaeological interest: one of the oldest known petroglyphs in the region. It is believed to date back to AD 900, and was first recorded by explorers in the year 1749. The carved symbols on the rock depict humans and animals and are believed to have been of religious significance to Native American shamans.

Check out some footage of Indian God Rock in this video from Phenomenal Travel 2:

2. Meadowcroft Rockshelter

Another significant archeological site in Pennsylvania is the Meadowcroft Rockshelter in Jefferson Township. It holds the oldest evidence of human life in North America. Many fascinating and scientifically rich artifacts have been found here, including arrow heads and other tools.

3. The Frick Mansion

The Frick in Pittsburgh memorializes the life of 19th-century industrialist and art collector Henry Clay Frick. Today, the estate includes an extensive art collection, a collection of antique automobiles, the historic Clayton mansion, and a greenhouse.

4. The Moravian Book Shop

The Moravian Book Shop in Bethlehem lays claim to the title of the oldest continuously operating book shop in the world. It has been open since 1745 and is a popular landmark in the Lehigh Valley.

5. Strasburg Railroad

The Strasburg Railroad is America's oldest short-line railroad. When you visit here, you can ride locomotives that are identical to the ones used in the late 19th century and into the 20th century. President Lincoln himself once rode these rails.

Let's head to the Strasburg Railroad in this video from yankeeinthesouth:

6. The Barnes Foundation

Once located in the original home of Albert C. Barnes in Merion, a few years ago the extensive art collection was relocated to a new building in Philadelphia. The foundation consists of a massive art collection including works by Picasso, Renoir, Cezanne, and many more old masters. The foundation offers a unique and perfectly curated look into art history, from the perspective of Barnes himself.

7. Mercer Museum

Located in Doylestown, the Mercer Museum is another place where historical artifacts have been left in a perfectly curated museum for you to admire. The massive collection of Henry Mercer, a 19th century anthropologist includes thousands of pre-industrial artifacts which are displayed in his massive, concrete castle.

8. Philadelphia's Camac Street

In the early 19th century, civil engineers experimented with a unique method of constructing streets, known as Nicolson Pavement. They would build the streets out of wooden beams; the method quickly fell out of favor due to its tendency to deteriorate and smell awful. Yet, one block of such pavement remains in Philadelphia, on Camac St. You can find this odd historical patch of road between Locust St. and Walnut St.

9. The Philadelphia Lazaretto Quarantine Station

Though you have probably heard of Ellis Island, you may not know about this Lazaretto Quarantine Station, which was once known as the Ellis Island of Philadelphia. Innumerable immigrants entered the country through its doors; it is America's oldest quarantine facility. Today, it stands vacant.

10. Concrete City

You can find the small, abandoned village in Nanticoke. The uniquely constructed concrete buildings were built in 1911 to house coal workers and their families. The development was abandoned because the concrete buildings proved unlivable; humidity would condensate on the buildings' walls and there was no plumbing. Today, the remaining structures provide an interesting look into the lives of past locals.

Explore Pennsylvania's Concrete City in this video from Post 10:

What other hidden gems in Pennsylvania would you add? Share some of your favorites with us in the comments. Then check out some of the little-known natural wonders in Pennsylvania.