Shahdiz Castle

Shahdiz Castle, in Isfahan municipality, Iran, may have been first constructed during the pre-Islamic Sasanian period and was later rebuilt by Seljuq authorities.

An early phase of the site is attributed to a pre-Islamic origin, with later reconstruction linked to the Seljuq sultan Malikshah. Medieval attribution credits Malikshah with building at the location near his capital, though the castle likely had earlier foundations.

In the late eleventh century the fortress came under the control of the Nizari Ismailis. The chief missionary, Abd al-Malik ibn Attash, based his headquarters at Isfahan, and his son Ahmad ibn Abd al-Malik ibn Attash effected a takeover of the fortress around 1100. Ahmad concealed his intent by posing as a schoolmaster, converted members of the garrison, which were largely of Daylami background, and set about re-fortifying the place in a manner similar to other Ismaili strongholds of the period. After securing the position he began to collect taxes from surrounding districts, and contemporary reports state he had converted some 30,000 people in Isfahan.

In 1107 the Seljuq sultan Muhammad I Tapar led a large campaign against the castle. Negotiations included a year-long religious debate, but Ahmad refused the terms offered and made a final stand. The garrison was overcome, many defenders were killed or fled, and Ahmad was captured. He and his son were executed and their heads were sent to the Abbasid caliph al-Mustazhir in Baghdad. Following the fall of the fortress, the sultan ordered Shahdiz demolished, and the nearby Khanlanjan fortress was apparently destroyed as well, a measure taken to prevent the site from being used again by the Nizari Ismailis. The loss of Shahdiz marked the end of Nizari Ismaili influence in the Isfahan area.