Octagonal. According to official website, Yizheng Tianning Temple Tower, Yizheng Tianning Temple Tower is a provincial-level cultural relics protection unit, located on the south bank of Hecheng, facing the Drum Tower across the river. The outside of the tower is octagonal, and the outside is corridor, with brick and wood structure. The interior of the tower is square, strewn at random, and the overall momentum is spectacular.