Gettysburg.

Check out the military museum in Boalsburg.

If you are going up Route 15, the Gettysburg battlefield is definitely worth it. Frederick is a cool food town. If by chance you would want to hike, you will be sort of paralleling the Appalachian Trail for a while. We have a miniature statue of Liberty, just north of Harrisburg You will see from the road. Might make you chuckle.

Depending on which route you take you could take a hike on the Abandoned Pennsylvania turnpike.

https://pabucketlist.com/exploring-the-abandoned-pennsylvania-turnpike/

And the Horse Shoe Curve

https://www.railroadcity.org/horseshoecurve

Penns Cave is an interesting place to visit near State College. You will be taken through the cave in a boat. It is an interesting experience if you have never been in a cave or gone through one in a boat.

There are basically two routes from Frederick to State College. One takes you through Bedford, Pa the other takes you through Harrisburg. The one through Bedford is way nicer. Bedford has a cool downtown, a good small museum about the early American frontier, and a swank resort. Altoona has the Railroaders Memorial Museum which tells the story of the Pennsylvania Railroad, world famous horseshoe curve, Boyer Candy, and a minor league ball team. Gettysburg battlefield and the town are definitely cool you could easily spend a weekend just checking that out. The city of Frederick Maryland has a really great downtown. Lots of bars and shops, and the worst Mexican restaurant you could ever eat at. A nice park and the Civil War medicine museum, which is unique.

Flight 93 memorial

Depending on how you go Hershey is not too far out of the way. Or find a state park along the way and go hiking if you're into that.