The largest temple complex on Mount Lao is that of the Temple of Supreme Purity (), a Taoist temple that was first built during the Northern Song dynasty with the present structures dating to the reign of the Wanli Emperor in the Ming dynasty. The temple is located near the coast, below Pantao Peak on the southeastern foot of Mount Lao and is hence also known as the Lower Temple (), The main structure of the temple is the Hall of the Three Pure Ones () with houses statues of the Taoist Trinity (the Grand Pure One, the Supreme Pure One, the Jade Pure One). It is flanked by the Three Emperors Hall (to the left, ) and the Three Officials Hall (to the left, ). The Three Emperors Hall enshrines statues of Fuxi, Shennong, and the Yellow Emperor. In the Three Officials Halls are the statues of the Three Gods (the God of Heaven, the God of Earth, and the God of Water) along with other statues, such as of the warrior god Xuan Wu and of Lei Gong, the God of Thunder. Two ancient Cypress trees in front of the Three Emperors Hall are said to have been planted during the Han Dynasty. Two old camellia trees are standing in front of the Three Officials Hall. On the walls outside of the Three Emperors Hall an imperial decree by Genghis Khan granting Daoism protection. A natural feature on the grounds of the temple is the Shenshui (Immortal Water) Spring that is fed by Mount Lao's considerable underground waters. The Qing dynasty writer Pu Songling is said to have resided in the Temple of Supreme Purity in his later years. His stories The Taoist Priest of Laoshan () and The Flower Nymphs () from the collection Strange Stories from a Chinese Studio are set on Mount Lao with the latter story specifically referring to peonies and camellias in the Temple of Supreme Purity.