Ptolemais (Greek: Πτολεμαΐς) was one of the five cities that formed the Pentapolis of Cyrenaica, the others being Cyrene, Euesperides (later known as Berenice, now Benghazi), Tauchira/Teuchira (later Arsinoe, and now Tocra), and Apollonia (now Susa).

[6] During the reign of Justinian I the city was rebuilt, but it never regained its powers and was again destroyed during the Muslim conquest of the Maghreb in the 7th century.

Important sculptures and inscriptions have also been found within the city, including imperial edicts such as that by which Diocletian attempted to fix prices.

In May 2011, a number of objects excavated from Ptolemais in 1937 and held in the vault of the National Commercial Bank in Benghazi were stolen.

Looters tunnelled into the vault and broke into two safes that held the artifacts which were part of the so-called Benghazi Treasure.

[10][11][12] Ptolemais became a Catholic Church diocese at an early stage, since it seems to have been the see of the Pentapolitan bishop Basilides to whom, in a letter of about 260 quoted by Eusebius,[13] Pope Dionysius of Alexandria said he had sent a copy of a commentary on Ecclesiastes.

The First Council of Nicaea confirmed the custom whereby the bishop of Alexandria held authority over the churches in the Pentapolis, although they were not situated in the same Roman province.

Synesius was bishop of Ptolemais from about 407 to 413, and was succeeded by his brother Evoptius, who took part in the Council of Ephesus (431), which condemned Nestorius.