On crisp, clear days, the eagle’s-eye views from the trilevel, glass-curtained Penobscot Narrows Observatory range from Mount Desert Island, home to Acadia National Park, to Mount Katahdin, Maine’s tallest peak. The observatory caps a 447-foot-tall bridge tower rising out of Fort Knox, a state historic site named for George Washington’s first Secretary of War. Construction on the sprawling granite fort, built to protect the upper Penobscot River from attack, began in 1844. Although it was neither finished nor utilized in battle, it’s a beauty. Among its prizes are two complete Rodman cannons and eye-candy vistas over Bucksport’s waterfront and Verona Island. Bring a flashlight and waterproof footwear to explore the underground passageways.
