Guldursun-Kala, also Guldursun Qala, in modern Karakalpakstan, Uzbekistan, was an ancient fortress in Chorasmia built in the 12th century CE.[1] It is one of the largest fortresses of Khwarezm, with perimeter walls of about 1 kilometer in total length, and an internal area of about 6.4 hectares (64,000 square meters, or 15.8 acres).