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Falak-ol-Aflak Castle, in ancient times was known as Dežbār as well as Shāpūr-Khwāst, is one of the most impressive castles in Iran. It is situated on the top of a large hill with the same name within the city of Khorramabad, the regional capital of Lorestan province. This gigantic structure was built during the Sassanid era (226–651).
The Khoramabad River runs past the eastern and south-western side of the Falak-ol-Aflak hill providing the fortress with an element of natural protection. 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 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.
The foundations of the actual castle measure approximately 300 meters by 400 meters. The height of the entire structure, including the hill, reaches to 40 meters above the surrounding area.
The castle itself covers an area of 5,300 square meters. It is 2,860 meters in perimeter and its tallest wall is 22.5 meters high. This space is divided into four large halls, and their associated rooms and coridors. The rooms all surround two courtyards with the following measurements: the first courtyard measures 31x22.50m and the second 29x21 meters. When originally built the castle used to have 12 towers, but only 8 remain standing today.
The building's entrace is situated towards the north, within the body of the northwestern tower.
The water well of the fortress lies in the area behind the first courtyard. Reaching a depth of 40 meters, the majority of the well's shaft is carved into the rock in order to reach the source of the Golestan spring. The well remains usable to this day.
The materials used in the construction of the fortress are mud-bricks, mud-fired bricks, stone, wood, and mortar.
Wikipedia