Portus Iulius

Portus Julius, on the north-western shore of the Gulf of Naples near Baiae, was the first harbour built expressly as a base for the Roman western naval fleet, the classis Misenensis. It was named after Julius Caesar, the great-uncle and adoptive father of Octavian, and the Julian clan. The port was protected by the Misenum peninsula. Today, its remains lie largely submerged, a consequence of the region’s volcanic bradyseism, which has slowly raised and lowered the coastline. Concrete piers, warehouses and the outlines of the basin can still be traced beneath the water, a quiet, ghostly relic of the naval power that once moored here.

Description via source. Coordinates and heritage data from the Atika atlas.