located 43 km east of Ardakan, Chak chak is one of the most important Zoroastrian pantheons. This historical pantheon is dating back to the Sassanid era. each year on 16th of June, Zoroastrians from around the world gather in this place for Mehrgan ceremony which is a sort of pilgrimage. There are some mythes about this place including the one about this place being where the Sassanid princes went inside the mountain and disappeared. This holy site includes places for the pilgrims to settle during the Mehrgan ceremony.