Khorramabad lies in a long, wide gorge sandwiched by dry, impressive crags in which at least five Palaeolithic cave-dwelling sites have been found. Historians disagree as to whether Khorramabad was the site of Shapurkhast or of Samha. Both are ‘lost’ ancient cities that had advanced irrigation and milling systems over 1500 years ago, judging from archaeological clues such as the Gerdab-e-Sangi cistern. In the Middle Ages a fortified central citadel was built here by the Atabegs, the powerful clan who ruled Lorestan from the 12th century until subjugated by Shah Abbas around 1600. The citadel later became the residence of Persian governors, who developed it into a classical fortress that soared so impressively that it became known as Falak-ol-Aflak (Heaven of Heavens). In the 1830s the Persian governors who occupied the citadel moved into a mansion (now a military academy) at its base and the fortress became a prison. It’s now an interesting museum.