Gerdab-e Sangi is a historical stony whirlpool that belongs to Sasanid Era and it is located at the center of Khorram Abad, in the middle of the ancient texture of the city, next to Takhti Square. Gerdab-e Sangi is circular and it is constructed using stone and mortar around a spring to organize the water from it and then to transfer water to various regions of the ancient city of Shapoor via a canal.  The spring of Gerdab-e Sangi has a discharge almost all days of the year. Gerdab-e Sangi has been registered as a national monument of Iran.