The emperors of the Ming (1368 - 1644) and Quing (1644 - 1911) dynasties held rituals at Tian Tan or Temple of Heaven, built in 1420, to offer sacrifices to heaven during the winter solstice, to pray for good harvest in the spring and for rain in the summer. The northern part of the park is semicircular, representing the heaven, where the Hall of Prayer for Good Harvests is located, and the southern part is square, representing the earth, where the Round Altar is located; in between lies the Imperial Vault of Heaven.