Why is it called the Forbidden City in Beijing?

People call Beijing the Forbidden City because it is the place where the emperor lived. In ancient times, the emperor claimed to be the son of heaven and earth. Many ancient books called the Heavenly Palace where the Emperor of Heaven lived "Purple Palace" or "Wei Zi Palace". Purple refers to the purple star wall. The ancients believed that the purple wall in the stars in the sky was located in the center, and the emperor was inlaid on both sides of the purple wall, so the purple wall was synonymous with the emperor. The emperor is the highest monarch in the world, and the palace where he lives is forbidden to the Lebanese people, so people call the place where the emperor lives the Forbidden City.