On the way back from Acadia National Park, I stopped in Bucksport, Maine, on the Penobscot River. I toured around Fort Knox State Park. The fort was built in the mid-1800s due to anti-British resentment and boundary claims between the UK (with it’s land in Canada) and the US.
Fort Knox is also the site of the Penobscot Narrows Bridge. The bridge includes an observatory–the only one of its kind in the US. Unfortunately, it was closed when I was passing through.