Commissioned into existence in 37 B.C. by the famous military leader and engineer Agrippa at the behest of Octavian.

Soon the harbor could not be used anymore for military purposes, necessitating the construction of a new harbor to the west (Misenum).

Portus Julius from then on was a prosperous civil harbor, developing into a suburb of Puteoli to the east.

Remains of docks, cisterns, and repair workshops are evident today.

The rediscovered mosaic has a wave frame in black and pink tiles on a white background, it once decorated the floor of a room of the Portus Julius.

Due to seismic activity, many remains of the city and Baiae to the west disappeared underwater, where they can still be seen by divers and from special boats.