Why is the Forbidden City called the Forbidden City?

The name of the Forbidden City comes from the metaphor of Wei Zixing Garden. Ancient astronomers in China once divided the stars in the sky into three constellations, twenty-eight constellations and other constellations. The three walls include Taiwei Garden, Ziwei Garden and Tianshi Garden. Ziweiyuan is in the middle of the three yuan. According to the long-term observation of celestial bodies in space, ancient astronomy in China believed that Wei Zixing was located in the middle of the sky and its position was eternal, so it became a constellation representing the Emperor of Heaven. This is the residence of the Emperor of Heaven. Therefore, the heavenly palace where the Emperor of Heaven lives is the Purple Palace. Forbidden, on the other hand, is better understood, which means that the palace is the royal base camp and no one else is allowed to come here.