In Libanius' speech For the Temples (Or. 30), sometimes regarded as the crowning work of his career, he refers to an unnamed city in which a great pagan temple had recently been destroyed; the date of the speech is disputed, but must be in the 380 s or early 390 s, near the end of the speaker's life. After deploring the actions of a governor appointed by Theodosius, often identified with the praetorian prefect Maternus Cynegius, Libanius continues (30.44–5):
Let no-one think that all this is an accusation against you, Your Majesty. For on the frontier with Persia (πρὸς τοῖς ὁρίοις Περσῶν) there lies in ruins a temple which had no equal, as one may hear from all who saw it, so very large was it and so very large the blocks with which it was built, and it occupied as much space as the city itself. Why, amid the terrors of war, to the benefit of the city's inhabitants, those who took the city gained nothing because of their inability to take the temple as well (τοῖς ἑλοῦσι τὴν πόλιν οὐκ ἔχουσι κἀκεῖνον προσεξελεῖν), since the strength of the walls defied every siege-engine. Besides that, one could mount up to the roof and see a very great part of enemy territory, which gives no small advantage in time of war. I have heard some people disputing which of the two sanctuaries was the greater marvel, this one that has gone, or one that one hopes may never suffer in the same way, and contains Sarapis. But this sanctuary, of such a kind and size, not to mention the secret devices of the ceiling and all the sacred statues made of iron that were hidden in darkness, escaping the sun – it has vanished and is destroyed.
Jacques Godefroy (Gothofredus), best known for his edition of the Theodosian Code, also produced the editio princeps of the speech For the Temples, supplying a Latin translation and extensive notes. He hesitated whether to identify the city in question with Apamea in Syria or with Carrhae, ‘urbs superstitione Gentilicia tum referta’, but opted for a third choice: Edessa, the capital of Osrhoene. In doing so he took for granted that a law of the Theodosian Code (16.10.8), in which the emperors order that a pagan temple in Osrhoene remain open, referred to the same temple; I shall argue below that this is incorrect. Opinion continues to be divided, though with a majority favouring Edessa. But this lay some ten or fifteen miles from the border with Persia, whereas Carrhae was directly on it, and is much more likely than Edessa to have had a temple from which one ‘could observe a vast area of enemy country’. The principal deity of Carrhae (Harran) was Sîn, the Moon God, said by some sources to be male, by others to be female. Describing how Caracalla was assassinated while on a pilgrimage to the god, Cassius Dio says that he had ‘set out from Edessa for Carrhae’, and was murdered on the way: according to Herodian, he was staying in Carrhae when he decided to go in advance of his army ‘and to reach the temple of the Moon, whom the local people greatly revere: the temple is a long way from the city [presumably Carrhae], so as to require a (special) journey’. Another emperor to visit the sanctuary was Julian on his march into Babylonia. Theodoret of Cyrrhus alleges that ‘he entered the sanctuary honoured by the impious’ and cut open a human victim, a woman suspended by the hair, in order to obtain an omen of his future victory.