In the centre of the area are the substructions of a temple, and on the south-east side are the remains of the theatre, built in the early imperial period, restored by Septimius Severus in 196-197 and again in the 4th or 5th century.
From the main building are the substructions of a smaller edifice, consisting of a series of rooms ranged round a square court, so that there are seven to each side besides a larger apartment at each corner.
The Arabic invasion at the end of the 7th century destroyed the Byzantine towns, and the place became the haunt of pirates, protected by the Kasbah (citadel); it was built on the substructions of the Punic, Roman and Byzantine acropolis, and is used by the French for military purposes.
Daux, discovered the jetties and the moles of the commercial harbour, and the line of the military harbour (Cothon); both harbours, which were mainly artificial, are entirely silted up. There remains a fragment of the fortifications of the Punic town, which had a total length of 6410 metres, and remains of the substructions of the Byzantine acropolis, of the circus, the theatre, the water cisterns, and of other buildings, notably the interesting Byzantine basilica which is now used as an Arab cafe (Kahwat-el-Kubba).
It is impossible without further excavation to reconcile the remains - mainly of substructions - with the elaborate description of his villa given by Pliny (cf.
Near by are the substructions of a temple of Dionysus and a large altar, and also a gymnasium with arrangements for bathing.
Besides these, in 1900 the substructions of a temple of Apollo Daphnephoros were unearthed.
High, which forms the southern termination of the modern island still bears the substructions of the temple of Apollo Leucatas (hence the modern name Capo Ducato).
Substructions of masonry and connected with each other by grand staircases, rose one above the other on the hill in the form of the side of a pyramid, crowned on the highest terrace by the round temple of Fortune.
The site, now uninhabited, is marked by ruins - the substructions of an amphitheatre, parts of a great temple - which have furnished interesting inscriptions.
The lower town was situated on the north edge of the valley, close to the Via Appia, which descended into the valley from the modern Albano, and re-ascended partly upon very fine substructions of opus quadratum, some 200 yds.
The remains existing within them are entirely Roman-a row of vaulted substructions, a water reservoir and a mosaic with representations of fishes.
Another suburb lay below the town and on the promontory on the west of it; under the Hotel Sirena are substructions and a rock-hewn tunnel.