Fort Constantine, Fort Konstantin, Fort Constantin, or Fort Grand Duke Constantine may refer to:
Fort Konstantin (Germany), Koblenz, Germany Fort Constantin (Russia), Kronstadt, Russia Konstantin Battery or Fort Constantine, built in Sevastopol, Ukraine in 1840 Fort Constantine (Yukon) near Forty Mile, Yukon Fort Constantine, Canadian ship of the Fort ship type RFA Fort Constantine, a Royal Fleet Auxiliary ship