Falak-ol-Aflak - Credit: Wikimedia Commons
Falak-ol-Aflak () or Shapur Khast Castle () is a castle situated on the top of a ancient hill with the same name in the city of Khorramabad, the capital of Lorestan province, Iran. The castle is among the most important structures built during the Sasanian Empire (224–651 AD), and one of the engineering and architectural masterpieces of the world. 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", "Sabr-Khast fortress", "Dezbaz", "Khoramabad castle", and ultimately, the Falak-ol-Aflak Castle. It was first used for government and military purposes during the Sassanid Empire, and it later became the seat of Hasanwayhid, Buyid and Khorshidi governments. Read more on Wikipedia
Source: en.wikipedia.org