The Temple of Heaven is located in spacious Tiantan Park, south of the central city, and is China's largest existing complex of ancient sacrificial buildings. Occupying an area of 273 hectares with four gates at the cardinal points, and walls to the north and east, it is three times the area of the Forbidden City. The Temple of Heaven is less a religious site than a historical one. Dating to the 15th century, it was where the emperor made an annual pilgrimage to pray for good harvests. It is made up of several notable buildings, such as the Altar of Prayer for Good Harvests, Imperial Vault of Heaven and Circular Mound Altar.
Chinese emperors usually paid strong veneration to Heaven, the Supreme Being that governed the universe. They considered themselves the "sons of heaven" and showed great concern over the rituals of heaven worship. In early Ming Dynasty, both heaven and earth were worshipped here. After the Temple of Earth was built in 1530, Heaven alone was bowed down here. During each ceremony, the emperors worshipped heaven and prayed for a good harvest. The emperors visited the temple three times a year: on the 8th day of the first lunar month to pray for a good harvest; during the Summer Solstice to pray for rain; and during Winter Solstice to give thanks for a good harvest. In addition, the emperors also worshipped their ancestors and other natural phenomena such as the Cloud God, Rain God and Wind God. During past ceremonies each year, the Emperor left the Forbidden City through the Front Gate for the Temple of Heaven. No common people or foreigners were allowed to watch the Emperor's procession to the temple. They had to remain hidden behind closed doors and windows. Even women, including the Empress, were not allowed to take part in the procession.
In imperial days, the Chinese people believed that the sky was in circular shape and the earth was square. On the basis of this traditional concept, the circle was widely adopted in the design of the temple's main building. It is in accord with people's imagination of heaven.