Fort Halifax

Fort Halifax is a former British colonial outpost on the banks of the Sebasticook River, just above its mouth at the Kennebec River, in Winslow, Maine. Originally built as a wooden palisaded fort in 1754, during the French and Indian War, only a single blockhouse survives. The oldest blockhouse in the United States, it is preserved as Fort Halifax State Historic Site, and is open to the public in the warmer months. The fort guarded Wabanaki canoe routes that reached to the St. Lawrence and Penobscot Valleys via the Chaudière-Kennebec and Sebasticook-Souadabscook rivers. The blockhouse was declared a National Historic Landmark and added to the National Register of Historic Places in 1968.

Source: Wikipedia