Shushan - Here probably the lower town, which lay east of the upper one, and was of about the same size (compare the Esther 9:6 note).
Related Commentaries of Esther 9:15
Esther 9:15
15 For the Jews that were in Shushan gathered themselves together on the fourteenth day also of the month Adar, and slew three hundred men at Shushan; but on the prey they laid not their hand.