In the time of Darius I, Susa (located in modern-day Iran) became the administrative capital of the Persian Empire.
The citadel of Susa was a separate section that towered twenty-four meters above the rest of the city. On the citadel stood a palace of forty metres in height. This palace showcased the treasures of all the conquered territories of Persia. It had tiles from Babylon, cedarwood from Syria, silver from Africa, and many treasures of art. It is from this palace that Xerxes I ruled at the time of the events recorded in Esther. (Xerxes also had two other palaces, one in Babylonia and the other in Ecbatana.)
2 in those days when King Ahasuerus sat on his royal throne in Susa, the citadel,