Khorramābād, city, capital of Lorestān province, western Iran. It commands a river gap in the Lorestān mountains used by the main road from Khūzestān to the highland plateau. A summer market for the nomadic Lur tribes, it has lively bazaars and a strong garrison. On a ridge between town and river stand the ruins of Dez-e Sīāh (“Black Fortress”), the former seat of the governors of Lorestān, from 1155 to 1600. Pop. (2006) 333,945.