Carleton Martello Tower National Historic Site is off Hwy. 1 exit 120 (Digby Ferry) to 454 Whipple St. Completed in 1815, the circular stone fort played a central role in the defense of Saint John and the harbor until 1944. From the top of the fort's tower there's a panoramic view of the city, the harbor and the Bay of Fundy. In addition to the 1866 barracks and 1845 powder magazine, both restored, there's a visitor center with exhibits. An 11-minute audiovisual presentation describes the fort's history from its construction during the War of 1812 to the role it played during World War II.