Falak-ol-Aflak castle (in Khorram abad) is amongst the most important structures 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.