Fort Kent (Blockhouse)

Fort Kent, a hand-hewn cedar blockhouse built in 1839 at the confluence of the Fish and Saint John rivers, was added to the National Register of Historic Places on December 1, 1969 and declared a National Historic Landmark on November 7, 1973, per Wikipedia's article on the fort. It is preserved as the Fort Kent State Historic Site, corroborated by the Maine Bureau of Parks and Lands as Maine's "first, state-owned historic site," now functioning as a museum open for visits in summer.