The most mysterious fortress is Koi-Kreelgan-Kala. Its name is translated as "the fortress of the dead sheep." Among the dozens of fortresses of ancient Khorezm, this one stands out for its unique design. The rounded perimeter of the fortifications is not similar to any similar structure, as well as the shape of the internal buildings, the palace, and other structures. What it is connected with, what conditions are due, scientists are still wondering. The fort was an almost perfect circle, with towers performing defensive and observant functions. The central building - the citadel, was inside the fortification, and the gap between the wall and the building was filled with buildings. Everything was built from clay, but so soundly that from the 4th century BC stood for almost 400 years.
Near the fortress, as well as on its territory, many fragments of dishes were discovered, which was also made of clay. Judging by the magnificence of the wreckage, it belonged to a noble nobleman. The ruler was guarded by valiant warriors. Findings from arrowheads and other fragments of weapons indicate a good preparedness for the defense to meet with the enemy.
At the time of the discovery of the fortress, it was considered the oldest find in Central Asia. They found it by accident, during an expedition to the area of the ancient Khorezm kingdom, 1938. Archaeologists were at a loss at the sight of the unusual structure of the fortress and closely engaged in the study of its history. Having discovered statuettes of Zoroastrian deities Siyavush (the god of the sun) and Anahita (the goddess of rivers and seas) on the site of the fortress, conclusions were drawn about the Zoroastrian origin of Koi-Kreelgan-Kala. Also, these images are on the fragments of containers for liquids, utensils. The inscriptions on the ancient Khorezmyskies also opened up a lot of information to scientists, but they still could not fully find out the purpose of the fortress and the reasons for its special structure.