Kashan's ancient citadel, known as Qal'ah-i Jalali, is located in the southwest corner of the old city, and was once part of a larger system of fortifications that included city walls. The structure dates to the Seljuq period and is attributed to Sultan Malik-Shah I (r. 1073-1092/465-485 AH). Today, the remains consist of a double enclosure wall in the form of a dodecagon. The interior has given way to cultivated lands. One noteworthy feature of the citadel are the remaining domed ice houses (yakchal) that have survived from early modern times.

Sources: 

Nārāqī, Ḥasan. Āsār-i tārikhī-i shahristānhā-yi Kāshān va Naṭanz, 120-124. [Tehran: Anjumān-i āsār-i millī, 1348/1969].