Esther 1:2

1:2 In those days, as King Ahasuerus sat on his royal throne in Susa ¹  the citadel, ² 

Esther 9:10

9:10 the ten sons of Haman son of Hammedatha, the enemy of the Jews. But they did not confiscate their property.

¹ tn Heb “Shushan” (so KJV, ASV). Most recent English versions render this as “Susa.”

² tn The Hebrew word בִּירָה (birah) can refer to a castle or palace or temple. Here it seems to have in mind that fortified part of the city that might be called an acropolis or citadel. Cf. KJV “palace”; NAB “stronghold”; NASB “capital”; NLT “fortress.”