This is the restored Thaddeus Stevens Furnace in Caledonia State Park, Pennsylvania. The park is at the top of South Mountain on US 30 (the Lincoln Highway) between Gettysburg and Chambersburg. The park is one of my favorite places, and I really can't say why. It has some good hiking, including the Appalachian Trail. There is a pool and extensive picnic and camping facilities.
Stevens built this iron-producing furnace before the Civil War. In July 1863, a detachment of Confederate soldiers destroyed it on their way to Gettysburg. It was revenge for Stevens being a passionate and prominent abolitionist.