It's pretty wild to come across something like this just sitting out in the middle of the woods. But that's where furnaces needed to be in the good olde days, because they would cut down acres of trees for the charcoal to run the furnaces. Click here for a great and sad description of this process.
If you are more the archaeological type and want all the somnolent details, try this site. And if you love old maps like I do, check out this one on the Library of Congress website. I can't imagine that too many members of Congress need old maps of iron furnaces, but I guess they have to be ready just in case. If you love all old iron furnaces, go here.
Roaring Run Furnace is on the Roaring Run Trail, which runs along Roaring Run Creek to Roaring Run Falls. It is all very beautiful, as you can see by the smile on my face.