The section Grand Master of the Multitude of The Rites of Zhou says: “The place where the gnomon projects a shadow that is one chi and five cun in length at noon of the summer solstice is called the Centre of Earth, where Heaven and Earth, the four seasons, wind and rain, yin and yang, meet.” The ancient Chinese believed that the Centre of Earth and the Centre of Heaven constitute the axis of the universe. Building the capital in the “Centre of Heaven and Earth” suggests the legitimacy of a monarch.

The ancient Yangcheng, present-day Gaocheng Town, Dengfeng City, Henan Province, was initially referred to as the “Centre of Earth” and the “Centre of the World”. The “Centre of Earth” not only influenced the location of the capitals of the Xia, Shang and Zhou dynasties, but also served as a reference point in astronomical surveying. The Duke of Zhou’s Shadow-Measuring Unit and Observatory were established directly based on the conception of the “Centre of Heaven and Earth”.