Khorramabad ( ), alternatively romanized as Khorramābād, Khoramabad, Khurramabad, Khorram Abad, or Khur Ramābād, is a city and the capital of Lorestan Province, Iran. At the time of the 2016 census, its population was 373,416 persons. Khorramabad is situated on the Zagros Mountains. Khorramabad Airport is 3 km south of the city proper. Khorramabad is the largest Luri-speaking city in Iran. The city population is predominantly Lur and Kurds. Although not a major tourist destination, it is quite scenic and possesses several attractions, such as five Paleolithic cave-dwelling sites. In the city center, a tall citadel called Falak-ol-Aflak (The Heaven of Heavens), a relic of the Sassanid era, is now a nationally popular museum. History Pre-Islamic era Simash During the late third millennium B.C. and early second millennium B.C., when Simashki sovereigns was ruling on Elam, for the first time a fort was built on the peak of a natural cliff to protect the city against its enemies. Six hundred years later, Ellipi kings built a new fort on the ruins of the old one. Simash was the name of the place. It was the capital of Simashki dynasty. Shapurkhast In the texts of historians Shapurkhast has been considered one of the most important and developed cities of the region during this period. Falak-ol-Aflak castle ( Dež-e Shāpūr-Khwāst) was built by Shapur I the Sassanid king. Islamic era Probably in the late seventh century AD, Shapurkhast was conquered by the Arabs in 633 AD and destroyed and the people of Shapurkhast moved to the western part of Falak-ol-Aflak Castle, which offered plenty of water as well as safety. Hamdallah Mustawfi writes: "Khorramabad was a beautiful city, now it is destroyed." Hazaraspids The founder of the Hazaraspid dynasty was Abu Tahir ibn Muhammad, a descendant of the Shabankara chieftain Fadluya. Fadluya was initially a commander of the Salghurids of Fars and was appointed governor of Kuhgiluya, but eventually gained independence in Luristan and extended his realm as far as Isfahan. He assumed the prestigious title of atabeg. Safavid dynasty During the reign of the Safavid dynasty, Khorramabad was the administrative center of Luristan Province. In the wake of the demise of the Safavids, after the signing of the Treaty of Constantinople (1724) with Imperial Russia, the Ottomans conquered Khorramabad on the 6th of September 1725. Qajar dynasty In this period, the city of Khorramabad was limited to environs of Falak-ol-Aflak Castle.