Alamut was once a mountain fortress in the arid hills south of the Caspian Sea, about 100 km from present-day Tehran in Iran. Only ruins remain of this fortress today.
In 1090 the fortress was invaded and occupied by the powerful Hashshashin (Assassins), and was then fabled for its gardens and libraries. Marco Polo wrote that men the Assassin sheik (supposedly Hasan Ibn Saba) wanted to turn into killers would be drugged, deposited in the garden, and be allowed to dally there with all its joys. Later the men would be drugged again and removed from the garden. Upon waking up, they would be told that they could experience those pleasures again if they killed for the order.
It was destroyed in 1256 by Hulagu Khan as part of the Mongol offensive. The fortress itself was impregnable, but the Assassin sheik surrendered it without a real fight, in the vain hope that Hulagu would be merciful.