100,000 Why: Why is the Forbidden City called "Forbidden City"

The Forbidden City in Beijing was the imperial palace of the Yuan, Ming and Qing dynasties. Ancient people thought that the Emperor of Heaven, who dominated everything in the world, lived in Wei Zi Palace on Ziwei Star, which was the emperor's palace. Since the emperor calls himself "the son of heaven" and "the son of heaven", his residence will of course be called "Purple Palace". In addition, the emperor's official residence is heavily guarded and civilians are never allowed to approach. This is a "forbidden" place. Therefore, this palace is called the Forbidden City.