The quintessential wooden structure at the Temple of Heaven is the Hall of Prayer for Good Harvests. This stunning beamless Qinian Hall has three tiers pronounced with eaves. It is crowned with a conical, blue tile roof accented with a gilded orb reaching 125 feet. The 105 foot diameter is elevated on a 20 foot high, white marble base called the Altar for Grain Prayers. Qinian Hall is also surrounded by multi-level railings. Since it was built in 1420, two venerated ceremonies by the emperor were performed here each year. The ritual at the first lunar month was a prayer for a good harvest. In the summer was a religious request for adequate rain. Behind this is another exquisite structure: Imperial Hall of Heaven.