Editing Alamut Castle (section)

===Construction and intellectual development===
[[Image:Alamut.JPG|thumb|left|260px|Scaffolding by [[Iran's Cultural Heritage Organization]].]]
With Alamut now in his possession, Hassan swiftly embarked on a complete re-fortification of the complex. By enhancing the walls and structure of a series of storage facilities, the fortress was to act as a self-sustaining stronghold during major confrontations. The perimeters of the rooms were lined with limestone, so as to preserve provisions to be used in times of crisis. Indeed, when the Mongols invaded the fortress, Juvayni was astonished to see stored countless supplies in perfect condition to withstand a possible siege.<ref name="Eagle's Nest"/>{{rp|27}}

Next, Hassan took on the task of irrigating the surrounding villages of the Alamut valley.  The land at valley's floor was arable land, allowing for the cultivation of dry crops including barley, wheat and rice. In order to make available the maximum amount of cultivable land, the ground was terraced under Hassan's direction.<ref name="Eagle's Nest"/>{{rp|27}}

The construction of [[Alamut]]'s famous library likely occurred after Hassan's fortification of the castle and its surrounding valley. With its astronomical instruments and rare collection of works, the library attracted scholars and scientists of a variety of religious persuasions from around the world who visited it for many months at a time, hosted by the Isma'ilis.<ref name="Eagle's Nest"/>{{rp|27}} By and large the writings of the Persian Ismailis, both scientific and doctrinal, did not survive beyond the Alamut period. In addition to the rich literature they had already produced in Arabic, the relocation of the Ismaili center to Iran now prompted a surge in Persian Ismaili literature.<ref name="Short History"/>{{rp|121}}

One of the earliest losses of the library came during the early years of the [[Jalaluddin Hasan|Imam Jalal al-Din Hasan]]’s leadership at [[Alamut]]. In keeping with his principles of bridging the gaping relations between the Persian Ismailis and the broader Sunni world, [[Jalaluddin Hasan|Imam Jalal al-Din Hasan]] invited a number of religious scholars from the town of Qazvin to visit the castle's library and [[book burning|burn]] any books they deemed heretical.<ref name="Short History"/>{{rp|121}} However, it was not until under the direction of the Mongol ruler, [[Hulegu Khan]], when the Mongols ascended to the fortress in December 1256 AD, that the [[Alamut]] library was lost. With the permission of Hulegu, Juvayni explored the library and selected a few works he deemed worthy of salvaging, before the remainder was set aflame. His choice items included copies of the Qur'an, a number of astronomical instruments and treatises, and a number of Ismaili works.  An anti-Ismaili, [[Ata-Malik Juvayni]]'s personal leanings were the sole measure of heretical content of the library's doctrinal works.<ref name="Eagle's Nest"/>{{rp|66}} Thus, some of the richest treatises regarding the tenets of Ismaili faith were lost with his destruction of the library. From his tour and survey of the castle, Juvayni compiled a description of Alamut that he incorporated into his chronicle of the Mongol invasions, entitled ''[[Tarikh-i Jahangushay-i Juvaini]]'' ("The History of the World Conqueror").<ref name="History of Survival"/>{{rp|31}}