chapter 13-14._

"There were two Libraries of Alexandria under the Ptolemies, the larger one in the quarter called the Bruchium, and the smaller one, named 'the daughter,' in the Serapeum, which was situated in the quarter called Rhacotis. The former was totally destroyed in the conflagration of the Bruchium during Cæsar's Alexandrian War [see below: B. C. 48-47]; but the latter, which was of great value, remained uninjured (see Matter, _Histoire de l'École d'Alexandrie, volume 1, page 133 seg., 237 seq.)_ It is not stated by any ancient writer where the collection of Pergamus [see PERGAMUM] was placed, which Antony gave to Cleopatra (Plutarch, Anton., c. 58); but it is most probable that it was deposited in the Bruchium, as that quarter of the city was now without a library, and the queen was anxious to repair the ravages occasioned by the civil war. If this supposition is correct, two Alexandrian libraries continued to exist after the time of Cæsar, and this is rendered still more probable by the fact that during the first three centuries of the Christian era the Bruchium was still the literary quarter of Alexandria. But a great change took place in the time of Aurelian. This Emperor, in suppressing the revolt of Firmus in Egypt, A. D. 273 [see below: A. D. 273] is said to have destroyed the Bruchium; and though this statement is hardly to be taken literally, the Bruchium ceased from this time to be included within the walls of Alexandria, and was regarded only as a suburb of the city. {39} Whether the great library in the Bruchium with the museum and its other literary establishments, perished at this time, we do not know; but the Serapeum for the next century takes its place as the literary quarter of Alexandria, and becomes the chief library in the city. Hence later writers erroneously speak of the Serapeum as if it had been from the beginning the great Alexandrian library. … Gibbon seems to think that the whole of the Serapeum was destroyed [A. D. 389, by order of the Emperor Theodosius—see below]; but this was not the case. It would appear that it was only the sanctuary of the god that was levelled with the ground, and that the library, the halls and other buildings in the consecrated ground remained standing long afterwards."

_E. Gibbon, Decline and Fall of the Roman Empire,