Introduction to the Sheji Altar: The Sheji Altar is located in the core area of the inner altar. It was built in the 18th year of Yongle in the Ming Dynasty (1420). The altar is square, three-story, 0.96 meters high, the upper perimeter is 15.95 meters, and the middle perimeter is It is 16.9 meters long and the lower floor has a circumference of 17.85 meters. There are four steps on each side and it is built of blue and white stone. The upper layer is paved with five-color altar soil, namely east green, south red, west white, north black, and middle yellow, commonly known as "five-color soil", symbolizing "all the earth in the world is the king's soil"; in the center of the altar stands the "main stone", also It is called "Jiangshan Stone"; there is a low wall built around the altar, also called a wall. The emperors of the Ming and Qing dynasties routinely held sacrificial ceremonies here on the fifth day of the second and eighth lunar months every year to pray for a good harvest and peace for the country and the people.