The palace city, also known as the inner palace and the inner palace, is commonly known as the Forbidden City and the Purple Wall. It is where Zhu Yuanzhang lived, handled government affairs, received visits from Chinese and foreign envoys, and where members of the royal family lived. It is located in the innermost of the four city walls of Nanjing. One, surrounded by a royal river.
The palace city was built in 1366 by filling in the lake after divination by Liu Bowen, who was proficient in Feng Shui. Therefore, the terrain is high in the south and low in the north. The palace faces south, with a rectangular plan. The main body of the palace wall is about 950 meters long from north to south, 750 meters wide from east to west, and has a circumference of about 3.4 kilometers.
On the palace wall, there were four city gates at first, and six gates were rebuilt in 1382. The main gate in the south is the Meridian Gate, the left and right sides of the Meridian Gate are Zuoyemen and Youyemen, the west gate is Xihuamen, the east gate is Donghuamen, and the north gate is Xuanwumen. Xuanwu Gate, commonly known as "Houzai Gate", is taken from the Kun hexagram in the "Book of Changes": "The terrain is Kun, and a gentleman carries things with kindness." In front of the Meridian Gate, it is the place where imperial edicts are conveyed and the court issues announcements. It is also where the emperor punishes ministers with the "court staff".