Most Roman theaters lean against a hillside, using natural terrain to support the tiered seating. Sabratha had no hill. Its builders, working sometime around the turn of the 1st and 2nd centuries AD, constructed the entire cavea on a freestanding framework of arches and vaulted corridors, an engineering decision that made the building both more ambitious and more fragile than its hillside counterparts. The cavea was divided into three tiers: the lower ima cavea with 12 rows of seats split into six sectors, the media cavea with 7 rows across seven sectors, and an upper summa cavea that has since vanished entirely. At full capacity, the theater held approximately 5,000 spectators. Twenty-four arcades on the ground level funneled audiences through vomitoria into the seating bowl, while a network of corridors and service rooms ran beneath the tiers.

The stage wall, or frons scaenae, is the theater's masterpiece. Standing over 22 meters high across three colonnaded levels, it was reconstructed through anastylosis, the painstaking process of reassembling original pieces in their original positions. Archaeologists deduced each column's level by its height: 5.54 meters for the first floor, 4.90 for the second, 3.65 for the third. The marbles tell a story of imperial trade networks. First-level columns are pavonazzo marble imported from Phrygia in what is now Turkey. Second-level columns are white marble. The third combines pavonazzo and granite. All are Corinthian order, but no two are identical: some smooth, some vertically fluted, some spiraling, some mixed with fluting on two-thirds of the shaft. The effect, when the Mediterranean sun catches the stone, is of a wall that lives and breathes with shadow.

Below the stage, a low wall called the pulpitum separates the performance space from the orchestra. At most Roman theaters this wall is merely functional. At Sabratha, it holds a sequence of white marble reliefs that have no equivalent anywhere in the Roman world. Alternating semicircular and rectangular niches frame scenes that mix theatrical performance, political allegory, and mythology. In the central panel, a crowned woman personifying Sabratha shakes hands with a helmeted figure representing Rome, surrounded by soldiers raising open palms. Nearby panels depict Mercury carrying the infant Dionysus, Hercules in his Nemean lion skin, and the Judgment of Paris with Venus, Minerva, and Juno competing for the golden apple. Dancers with crotales mark the transitions between scenes. Some archaeologists date these reliefs to the reign of Septimius Severus, who was born in nearby Leptis Magna, and identify the bearded officiant in one sacrificial scene as Severus himself.

The theater's history is one of violent interruptions. Earthquakes in AD 365 severely damaged the structure. A fire followed, evidenced by layers of ash found during excavation. Private dwellings occupied the ruins. Byzantine builders quarried the stone for their own constructions. Sand covered what remained. The Italian colonial excavation from 1927 to 1937, led successively by Bartoccini, Giacomo Guidi, and Giacomo Caputo, produced what some archaeologists consider the finest anastylosis of any Roman theater. But the rear facade, crude and unfinished, strikes others as implausible. The site became a UNESCO World Heritage Site in 1982. War followed in 2011, and in 2016 the entire site was added to the World Heritage in Danger list as political instability raised fears of looting.

The most persistent threat is not human but geological. Sabratha sits on soft rock and sand along a coast prone to erosion. The calcarenite sandstone used in construction is highly susceptible to physical, chemical, and biological weathering, particularly from salt-laden sea spray. Without the stucco coating that originally protected the stone, the restored columns and walls are slowly dissolving. The public baths and harbor structures have already crumbled from storm damage. Breakwaters installed near the site are too small to offer real protection, and rising sea levels compound the problem year by year. In 1943, archaeologist Max Mallowan, husband of Agatha Christie, was stationed at Sabratha overseeing grain rations. He lived in a villa overlooking the sea and dined on fresh tuna and olives. The Mediterranean that made his assignment so pleasant is now reclaiming the ruins it once watched being built.