By the end of the year, Cassius' army had reached the twin metropolises of Mesopotamia: Seleucia on the right bank of the Tigris and Ctesiphon on the left. Ctesiphon was taken and its royal palace set to flame. The citizens of Seleucia, still largely Greek (the city had been commissioned and settled as a capital of the Seleucid empire, one of Alexander the Great's successor kingdoms), opened its gates to the invaders. The city got sacked nonetheless, leaving a black mark on Lucius' reputation. Excuses were sought, or invented: the official version had it that the Seleucids broke faith first. Whatever the case, the sacking marks a particularly destructive chapter in Seleucia's long decline.