The magnificent unreachable Fort of Alamut was once the residence of a religious group that came to be known as The Assassins. The Alamut Fort is part of the Qazvin Province and located in the North-East of Qasr Khan Village. The Fort is made 200 m above the ground and surrounded by 4 steep valleys make it very hard to reach especially for those who are not familiar with the area. although the time of its construction is not definite, it is estimated to the third century after Islam and made by the Daylamite but it was Hassan Sabah that turned it into an undefeatable place.
The fort had two main sections located on the West and Eastside. The entrance to the fort was through a series of twisted stairs made in a way that was accessible for livestock as well. the Watch Towers, Warehouses, Water Reservoir, Residential Spaces, and Mosques are the main sections of the Fort. many scientists used to live there, the Assassins Leader was a patron of art and science, giving refuge to many scientists.
When the Mongol Army attacked Iran, the fort was the last place to be conquered, but nevertheless, the fort was plundered. The only thing that survived the brutal attack was the books in the library.