At the foot of the San Giusto hill, by the sea, the Romans between the 1st-2nd century AD. built a large theater capable of holding between 3500 and 6000 spectators who, on the gratins built using the natural slope of the hill, attended outdoor entertainment shows: tragedies, comedies and some finds of helmets, it also seems to fights between gladiators.

The theater dates back to the 1st-2nd century AD. The act of foundation of the theater is documented by two tombstones, where word was made of the gift and dedication by the Tergestino knight Quinto Petronio Modesto, procurator of the Emperor Trajan and a character linked to the theater of the time.

With the passing of the centuries the theater was devastated, together with the Capitoline basilica and other public buildings, by the Lombard hordes and was gradually stripped of its architecture and buried by residential buildings.

In 1814 the architect Pietro Nobile, also guided by the name of the place “Rena vecia” (Old Arena), had drawn up a report on the hidden theater which was then proved to be correct during the excavations of 1937-38, years of the demolition of a part of the old city, where the amphitheater was unearthed.

During the excavation of the pit of the proscenium some statues came to light: one of a female figure 111 cm high, missing the head and other parts of the body, identified as a statue of Hygieia due to the presence of a snake descending from the left shoulder;

a bearded statue of Asclepius (118 cm), wrapped in the mantle and uncovered the upper part of the bust; the statue of the goddess Athena, 125 cm high, headless like that of Apollo, 102 cm high and Silenus (98 cm long), lying on a panther skin and resting on a stylized rock base and fragmentary pieces of the statue of Aphrodite including the head and cloak. Many other finds of archaeological interest came to light that are now visible at the Civic Museum of History and Art and at the Tergestino Lapidarium.