Lighting is washed out ... a tough shot to do with the shadows of the trees etc. but, in this care you might have been better off to reduce the subject to allow your camera to deal with the contrast.
Nice picture. Your highlights seem a bit overblown in the front of the structure. I think a shorter title might work better, such as 18th Century Iron Furnance. Also, it feels like it needs a little straightening.
I love American historical subjects, thanks for including more info in the title about it. Must have been a very bright day, I would like to see what it would look like with a little less exposure.
The light is rather harsh making the image a little flat, later in the day would have been better and the texture of both stone and grass could be seen, interesting spot though..
I think it needs a new title - too long and not necessary. Furnace would have been enough and to tell me it made canon balls is totally irrelevant. It would have been stronger with different lighting - darker - to bring out more of the character of the stone.