Introduction to the Praying for Grain Altar: The altar of the Praying for Grain Altar is a circular building that combines an altar and a hall. It was built based on the ancient saying of "worshiping the emperor under the house". The altar is three-story, 5.6 meters high, with a lower floor diameter of 91 meters, a middle floor diameter of 80 meters, and an upper floor of 68 meters. The hall is round, 38 meters high, and 32.7 meters in diameter. It has triple blue glazed tiles, round eaves, a pointed roof, and a gilded top. gold.