Introduction to the Yellow River Altar: The Yellow River Altar is composed of a square altar and a round altar, echoing the theory of a round sky and a round earth. The side length of the square altar is 99.99 meters, with a total area of 9999 square meters. It uses square pillar heads and is carved with four guardian spirits: green dragon, white tiger, red bird and Xuanwu in the east, south, west and north directions. The round altar in the middle has a cylinder head and a layer of green water. , two layers of green clouds, and three layers of green dragons, representing the yellow dragon flying between heaven and earth; the round altar is equipped with 5 passages, representing the five rows of gold, wood, water, fire, and earth.