Where in Maine Is This? [PHOTO]

Where the heck in Maine is this? I think it's wicked cool! I came upon this monstrosity during weekend adventures with my kids.  Here's one hint for you....it is the biggest of it's kind in the US. So....what is it and where is it?

If you know the answer, let us know below. All correct answers will go in a drawing for a prize pack from the Blimp Prize Vault. Good Luck!