 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.