Pozzuoli is famous for a number of things including the Roman Amphitheatre and the Macellum. Before we get to those, this is:
where St Paul landed on his way to Rome;
where Caligula ordered a temporary floating bridge to be built using trading vessels, stretching for over two miles from the town to Baiae, across which he proceeded to ride his horse. An astrologer had predicted that he had "no more chance of becoming Emperor than of riding a horse across the Gulf of Baiae;
the place where the first effective concrete in Roman times was made from the local volcanic sand, pozzolana;
a place which significantly demonstrates bradyseism activity (more later on this).
Seating approximately 40,000 and 74m by 41m, the Flavian Amphitheatre (Amphitheatrum Flavium) is the third largest in the Roman world after The Coliseum and the Capuan Amphitheatre.
In the historical past, part of the amphitheatre has been demolished and reused in local houses
Running under the amphitheatre floor are numerous passages and cells where animals were kept. The corridors in the left hand picture was probably roofed over with planks at arena level and there was some sort of trap door to provide access for animals etc. In the right hand picture, there would have been two floors with some unknown mechanism for opening the doors of the cages from below so that animals could get into the arena.
The size of the tunnels and the effort expended in their creation is astonishing. Each of the millions of bricks in the amphitheatre was hand made and then baked in a kiln using wood from local forests. Felling the forests caused erosion and the soil which was washed down the rivers eventually made a number of seaports (such as Pompeii), inland towns.
Calculating the number of slaves who must have been involved and its impact on the local economy would be an interesting exercise.
This was an arcaded square courtyard, surrounded by two-storey buildings. Shops lined the marble floored colonnade which had 34 granite columns around its edge. There was a Tholos in the centre of the square perhaps with a well for water and maybe where fish was sold or perhaps where the shrine to the gods of the market was kept.
The remains include three columns in cipolin marble which
show erosion from marine Lithophaga molluscs when, at an earlier time, the ground level was much lower due to Bradyseism, and sea-water could flow in. This is essentially a periodic raising and lowering of the ground level due to volcanic activity in the area, here by as much as 10m. The pillars were once below sea level, hence the mollusc damage. That sea flooding was a problem to the Romans is
evidenced by the walkways they constructed across the macellum floor. There is also a toilet in one
corner - typically a communal squat with a water trough for rinsing your sponge.