Ancient city in the Khuzistan lowlands of south-western Iran. Susa often fell into the hands of Mesopotamian powers, but also served as a major centre for the Elamite civilization of the Iranian highlands. It was first occupied in c. 4200 BC. After suffering political decline, Susa fell under the control of Assyria and a further succession of empires, but still remained an important site, even serving (550-330 BC) as a royal city for the Persians.