The Portus Julius was commissioned by Augustus and especially by his son-in-law Agrippa in 36
BC. to prepare for the battle against Sextus Pompey, transforming the access to Lake Lucrino and
creating a connection with Lake Averno.
The military function was short, given the movement of the fleet to Miseno as early as 30 BC. and
perhaps also to give space to that great business that had already developed on Lucrino itself,
namely oyster farming, linked to the figure of Sergio Orata and followed by many senators.
According to the various stories of various ancient authors, the strip of land that separated the
sea from Lake Lucrino, on which the legendary Via Herculanea also ran, immediately consolidated
interventions already at the temple of Julius Caesar, precisely to preserve the precious farms
during the storms.
Agrippa's intervention was remarkable, cutting the natural sandy tongue that divided the brackish
water of the lake from the sea. Strabo specifies that the Gulf of Avernus was deep and easy to
access, with the dimensions and characteristics of a port, but it was not used for this purpose
because the opposite lake Lucrino was shallow and very extensive. Pliny instead attributes to
Claudio the construction of the piers for the separation of Lake Lucrino from the sea.
According to scholars, little of what is preserved in the water can be traced back to the Agrippa
port facility, believing that the latter's works were a temporary expedient, obtained very quickly
and at low costs. Perhaps it was enough for Agrippa to reinforce the external embankment and
put the two lake basins in communication with the sea for the exploitation of an area already
suitable for both a shipyard, given the presence of extensive wooded areas along the banks of the
Averno, and as a training ground for the new 20,000 slaves improvised sailors.
But if not for military purposes, soon placed elsewhere, the port destiny of the area was marked:
an uninterrupted sequence of horrea, that is of warehouses, connected Puteoli to Portus Julius,
ready to welcome Egyptian wheat and other merchandise destined above all for the market of
Rome. A transit port, therefore, important for logistics through storage and redistribution, typical
of ports linked to the annona, that is, the grain supply service for Rome.
The area began to have its own definition thanks to aerial photos from the Second World War
onwards, but the first systematic searches in water had to wait until 1988-90, with investigations
at the remains of Lido Augusto. A quadrangular arcaded courtyard dating back to the 1st century
was identified. AD, considered part of a larger horreum built close to a domus, dating back to a
few decades earlier, incorporated into the transformations related to Agrippa's intervention, which
involved the insertion of commercial structures near mostly residential structures.
The interventions of the 90s also focused on a long structure originally believed to be a long pier
between two docks, in reality perhaps a long portico with attached covered rooms. Towards the
interior, the shore of the lake appeared to be regularized by an artificial quay with the remains of
even a roadway directed towards the Ripa Puteolana.
The latest studies (Gianfrotta) have focused on the analysis of individual warehouses and the
shape of the rooms, even on several floors, as well as of the materials found, such as wooden
barrels or whitebait deposits, perhaps to preserve some particular cereals. A very latest discovery,
like a small millstone, demonstrates the existence, in close correlation to the warehouses, of
artisan plants, mills and ovens, for a direct and local transformation and use of the deposited
In this context, the first active route in the area was established, coinciding with one of the points
with greater depth, equal to about four meters and close to the abandoned shoreline of Lido
Augusto: here you can see a complex of the Republican age with 6 floors in cementitious, that is
in small fragments of earthenware fragmented and cemented together, between which small
mosaic tiles were inserted to form stylized floros or rhombus grids. They are probably part of a
residence which was later joined by a series of warehouses, the colonnaded courtyards of which
are clearly recognizable.
The new itinerary: “Il Percorso delle Colonne”
Instead, the new path that will open to the public starts from the entrance channel to the ancient
Lucrino lake, built by Agrippa Wednesday 30 June. As soon as you get into the water it will be
possible to see the mighty banks of this long canal from which the ships for calmer waters had
Its banks must have been full of activity, as evidenced by the first easily recognizable remains,
namely two portals that give access to a large pool behind. The gargami (this is the technical
name of the stone jambs) are still crossed by deep grooves on which the perforated metal grate
ran, allowing the water to pass but nothing else. The hypothesis on the complex are varied, from
direct resale of fish to a plant for salting it (given the trays present behind it, perhaps for
evisceration) but it has also been hypothesized a connection with a simpler fullonica connected
with the well-known purpurrissimum puteolano, that is the dye for fine clothes.
From here begins a forest of walls between which it is easy to get lost. The reason is simple: what
can be observed today is the result of the superimposition of several buildings. It was built over
the centuries, between the first century. B.C. and the 5th century AD, that is at least 400 years,
completely modifying its function and orientation, but overlapping the previous remains. In
addition to new needs, it is likely that this happened, as seen in Baia, due to bradyseism, active
then as now: the lowering of the dry surface must have forced the level of the floors to be raised,
in order not to allow access to the water, in particular in these stretches then enclosed between
the sea and the lake.
Among these remains, a sequence of large collapsed columns in colored marble, probably part of
the decoration of the last building built here, immediately stand out: a large semicircular room
facing the canal, whose function we do not know but whose function we recognize. grandeur,
which could be admired by the ships entering the canal.
A little further, but at greater depth, a small apsidal room, characterized by the presence of a
circular base in the center of the semicircular space, seems to give us a small space of worship,
on which we need to further investigate. From here you go along what used to be a long and
narrow corridor, which ends with a narrow corner close to a large apse, built with imposing
blocks, against which we still recognize a mosaic floor, characterized by white tiles with a black
band along the edge.
A little further on, the landscape changes completely: crystalline white sand demonstrates the
absence of structures, if not a long and narrow pool. We interpret these remains as an ancient
garden with a euripus in the center, that is, a tub to decorate this very large space. At its end, a
surprise that demonstrates the overlaps we were talking about: we meet the remains of twelve
columns in bricks, still in their original position but cut upwards, to make room for the new garden.
Immediately afterwards, the panorama changes again, with imposing structures: among these, a
mosaic of black tiles with marble slabs inserted around a quadrangular basin, also covered with
marble. We are again in luxurious surroundings, on the opposite side of the large garden. Long
corridors with small semicircular fountains describe the richness of these spaces, on which
another large building was then superimposed: a basilica? civil or Christian? the rectangular
shape with a large apse at the bottom is well suited to both solutions, and its remains such as the
large cipollino columns tell us only that the decorative level was high.
Here the tour ends, after more than 200 meters of fins, but the investigations still to be carried out
are certainly not finished, to better try to define these remains submerged by the sea and to
investigate the structures that continue beyond.
The activity implemented by Pafleg intends to continue the research process started last year on
this very important area, namely the B zone of the submerged park of Baia. In addition to the best
known and most popular zone A, that is the district of rich residences around Punta dell'Epitaffio,
the continuity of the remains submerged by bradyseism continues uninterrupted towards the port
of Pozzuoli, with this large nucleus just reopened at the entrance channel of the Portus Julius. To
know more and more, but also to show more and more, to all users, from divers to snorkelers, but
also to boats with a transparent bottom or canoes. More knowledge and use also corresponds to