Waqiu altar is a 3402-piece fan-shaped Shi Zhuan. Waqiu altar is a three-story open-air circular platform built in Jiajing period of Ming Dynasty in China, also known as altar. It consists of Waqiu, Imperial Dome and its affiliated buildings, kitchen, three warehouses and sacrificial pavilions. Located in the south of the Temple of Heaven, it is the place where the emperor worships heaven from the winter solstice. Because it is a sacrifice to the Temple of Heaven, the whole structure of the dome is a clever use of mathematics. The stone components of the altar, steps and railings all take nine or multiples of nine, that is, positive numbers, to symbolize the sky. The circular slate in the center of the altar is called Tianxin Stone (a stone with a trillion sights). Standing on it, you shout or knock, and the voices around you echo. It sounds loud, as if you are ready to respond.