Fort McClary is a former defensive fortification of the United States military located along the southern coast of Maine at Kittery Point. Built at the mouth of the Piscataqua River, it was used primarily throughout the 19th century to protect approaches to the harbor of Portsmouth, New Hampshire, and its U.S. naval shipyard. The property and its surviving structures, including a blockhouse dating from 1844, are now owned and operated by the State of Maine as Fort McClary State Historic Site.