20. Within this circuit is Adiabene, which was formerly called Assyria, but by long custom has received its present name from the circumstance, that being placed between the two navigable rivers the Ona and the Tigris, it can never be approached by fording; for in Greek we use διαβαίνειν for to "cross:" this was the belief of the ancients. 21. But we say that in this country there are two rivers which never fail, which we ourselves have crossed, the Diabas, and the Adiabas: both having bridges of boats over them; and that Adiabene has received its name from this last, as Homer tells us Egypt received its name from its great river, and India also, and Commagena which was formerly called Euphratensis, as did the country now called Spain, which was formerly called Iberia from the Iberus.[142] And the great Spanish province of Boetica from the river Boetis.[143] 22. In this district of Adiabene is the city of Nineveh, named after Ninus, a most mighty sovereign of former times, and the husband of Semiramis, who was formerly queen of Persia, and also the cities of Ecbatana, Arbela, and Gaugamela, where Alexander, after several other battles, gave the crowning defeat to Darius. 23. In Assyria there are many cities, among which one of the most eminent is Apamia, surnamed Mesene, and Teredon, and Apollonia, and Vologesia, and many others of equal importance. But the most splendid and celebrated are these three, Babylon, the walls of which Semiramis cemented with pitch; for its citadel indeed was founded by that most eminent monarch Belus. And Ctesiphon which Vardanes built long ago, and which subsequently King Pacorus enlarged by an immigration of many citizens, fortifying it also with walls, and giving it a name, made it the most splendid place in Persia--next to it Seleucia, the splendid work of Seleucus Nicator. 24. This, however, as we have already related, was stormed by the generals of Verus Cæsar, who carried the image of the Cumæan Apollo to Rome, and placed it in the temple of the Palatine Apollo, where it was formally dedicated to that god by his priests. But it is said that after this statue was carried off, and the city was burnt, the soldiers, searching the temple, found a narrow hole, and when this was opened in the hope of finding something of value in it, from some deep gulf which the secret science of the Chaldæans had closed up, issued a pestilence, loaded with the force of incurable disease, which in the time of Verus and Marcus Antoninus polluted the whole world from the borders of Persia to the Rhine and Gaul with contagion and death.