Falak-ol-Aflak Castle is a castle situated on the top of a large hill with the same name within the city of Khorramabad, the regional capital of Lorestan province, Iran. This gigantic structure was built during the Sassanid era (224–651).
The Khoramabad River runs past the eastern and south-western side of the Falak-ol-Aflak hill providing the fortress some natural protection on those sides. Today, the western and northern sides of the hill are bordered by the residential districts of Khorramabad.
Falak-ol-Aflak castle is amongst the most important st ructures built during the Sassanid era. It has been known by a number of names since it was built over 1800 years ago. Recorded names have referred to it as Shapur-Khast or Sabr-Khast fortress, Dezbaz, Khoramabad castle, and ultimately the Falak-ol-Aflak Castle.Falak ol aflak castle is in center of Khorramabad city. Under the Pahlavi dynasty, after being used as a prison until 1968, it was transformed into a museum complex. Wikipedia