The round fortress Chilpyk can be found on a hilltop 43km south from Nukus near the highway to Urgench. The diameter of the building is 65 meters, circumferential walls are preserved to the height of 15m. It is surprising that neither traces of the buildings inside the fortress nor any loopholes on the walls can be seen. All internal part is a clay court, paved with black sandstone. The base of the fortress dates back to the end of the 1st century BC - 1st century AD.
The fact that a lot of debris of Zoroastrian ossuaries (bone repositories) were found on the slopes of the hill provides a reason to believe that Chilpyk served as the "tower of silence" or dakhma. It is the name for structures where Zoroastrians used to put dead bodies before burial. After the bones were cleaned of flesh by birds of prey and dried in the sun they were buried in ceramic ossuaries. After the Arab conquest and conversion of Khorezmians to Islam Chilpyk changed its purpose. The fortress was rebuilt to be used as a guard and signal tower.