Ziweiyuan sanyuan

The "purple" in the Forbidden City refers to Huan.

Lagerstroemia indica ring is located in the highest place in the middle of the sky, with 15 stars. This group of stars is considered to be the palace where the Emperor of Heaven lived, and it is called "Purple Palace" in "Guang Ya Shi Tian". The Book of the Later Han Dynasty also said: "There is a purple palace in the sky, where the gods live, and a royal palace, just like that." Therefore, the palace on the earth should be built in the sky, and it is a pattern of "ruling by virtue is like Beichen, living in its place, and the stars are * * *", similar to the Tiangong.

"Forbidden" means forbidden area. This palace, also known as ouchi, is heavily guarded. So the palace in Beijing is called the Forbidden City.