قلعة ألموت
Rukn al-Dīn al-Hasan ibn Muhammad Khurshāh (or Khwarshāh) () (1230-1257) was the son of ‘Alā’ ad-Dīn Muḥammad III and the 27th Isma'ili Imam. He was also the fifth and final Nizari Isma'ili Imam who ruled at Alamut. The Imam was the eldest son of Imam ʿAla al-Din Muhammad and succeeded his murdered father to the Imamate in 1255. Imam Rukn al-Din engaged in a long series of negotiations with the invading Mongols, and under whose leadership Alamut Castle was surrendered to the Mongol Empire marking the end of the Nizari state in Persia