This amphitheatre is very much smaller than either the Colosseum in Rome, or the amphitheatre at Capua; the superstructure is in a very ruinous state, but the substructure is almost perfect, and the work is much more highly finished than in either of the others. There are considerable remains of rich stucco ornament on the vault over the passage to one of the side doors. The arena is nearly intact, and is of brick, carried on vaults, what the Italians call _pensile_; this word does not mean literally hanging, but hollow underneath; and this brick floor is full of square holes for trap-doors; round the edge of each is a deep groove, as if for a cover to fit into, which may very well have been made water-tight. Signor Scherillo, a native of Pozzuoli, and now a canon of the cathedral at Naples, has published several papers on this amphitheatre in the _Atti dell’ Accademia di Archeologia, Letteratura e belle Arti di Napoli_. He is of opinion that the arena was flooded to the depth of about three feet, or about half way up the _podium_; the water would only cover the two or three lower steps, and there were probably also water-tight doors at the foot of them. At a short distance in front of the _podium_ is a channel about a foot deep, in which probably a beam of wood has lain, and at intervals of ten or twelve feet is a square hole, evidently for a beam of wood to have stood in, no doubt the lower part of the frame for the netting to keep off the wild beasts from the people in the lower gallery, as in the Colosseum, and probably carried up as poles or masts to receive the lower ends of the cords to carry the awning; there are also remains at the top of the outer wall of the same arrangement of fixing the masts there as in the Colosseum, and the same thing can be seen in many other amphitheatres where the outer wall remains perfect. This amphitheatre is entirely of the time of Hadrian, a beautiful piece of construction. It seems to have been a favourite show-place of the Emperors on state occasions, for the upper classes and foreigners, when the fleet was assembled in the Bay of Naples, in which the Cape of Misenum is one of the promontories near this spot. The enormous reservoir of water for the supply of the fleet, called the _Piscina Mirabilis_, is also not far off; and the amphitheatre belonged to the great imperial villa, originally of Nero, in the bay adjoining.