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Nahāvand Castle ( fa, قلعه نهاوند) was an ancient castle from Sasanian Persia that was located in what is now the city of Nahavand in Hamedan province, Iran. The fall of this castle in the 
Battle of Nahavand
The Battle of Nahavand ( ar, معركة نهاوند ', fa, نبرد نهاوند '), also spelled Nihavand or Nahawand, was fought in 642 between the Rashidun Muslim forces under caliph Umar and Sasanian Persian armies under King Yazdegerd ...
was a major turning point in the Islamic conquest of Persia. Nonetheless, the castle survived up until the time of Naser al-Din Shah Qajar. It was said that when digging a qanat, Naser al-Din Shah found a treasure. He then ordered the castle to be destroyed in order to find more treasures; however, no more were found.
References
Sasanian castles Castles in Iran Military history of Iran Buildings and structures in Hamadan Province Ruined castles in Iran Demolished buildings and structures in Iran {{Iran-castle-stub National works of Iran