Portus Julius (alternatively spelled in the Latin "Iulius") was the first harbor specifically constructed to be a base for the Roman western naval fleet, the classis Misenensis. (The eastern fleet was in the Port of Ravenna.) The port was on a peninsula located at the northern end of the gulf of Naples, and incorporated two bodies of fresh water: Lake Lucrino, Lake Averno, and the natural inner and outer harbor behind Cape Misenum. Portus Julius was so-named in honour of Octavian's (later to become Caesar Augustus) great-uncle and adoptive father, Julius Caesar and the Julian clan.