The words "morning bells on the Golden Gate, countless doors open, and a thousand officials floating on the jade steps" and "thousands of families" in Cen Shen's poems are exactly the Daming Palace in the prosperous Tang Dynasty. In addition to Daming Palace, there are also Taiji Palace and Xingqing Palace, collectively known as the "Three Nei". One city, two cities and three inner cities constitute the unique landscape of the ancient capital Chang'an. Why does Chang'an have to squeeze into three palaces when it's so good? Daming Palace, located in the east of Chang'an City, is known as the "Eastern Palace". The palace has a circumference of 7,375 meters and an area of ??approximately 2.95 square kilometers, which is more than four times the size of the Forbidden City in Beijing. It is the largest palace among the three cities. The Tang Dynasty lasted for 289 years and had 22 emperors, 17 of whom handled government affairs in the Daming Palace. Song, a historian and geographer of the Northern Song Dynasty, recorded in "Chang'an Chronicles": "In the eighth year of Zhenguan (634), it was designated as Yong'an Palace. The following year, it was renamed Daming Palace in preparation for the emperor's Qing Dynasty, and hundreds of officials donated money to assist him. In the third year of Longshuo (663 years), it was built by Da Jia Xing and named Penglai Palace. In the first year of Xianheng Period (670 years), it was changed to Hanyuan Palace and found Daming Palace. "According to the "New Records of Erjing", "South of Daming Palace. It connects Beijing to the north and the northeast corner of Beijing to the west. At first, Emperor Gaozong felt that the palace was wet and the house was covered. "From the comprehensive information, it is not difficult to see that the Daming Palace was built. It was completed and delivered nearly 30 years after the reign of Emperor Taizong and Emperor Gaozong of the Tang Dynasty.

Taiji Palace, located north of the central axis of Chang'an, is called "Xinei" compared with Daming Palace. The entire palace is 1,285 meters wide from east to west, 1,492 meters long, and covers an area of ??1.92 square kilometers. The palace is divided into three parts: the Korean area, the sleeping area, and the garden area. Along the north-south central axis of the palace city, there is Prince East Palace on the east side and Yeting Palace on the west side. The main buildings are Tai Chi Hall, Liang Yi Hall, Cheng Qing Hall, Wude Hall, Ganlu Hall and Lingyan Pavilion. Taiji Palace was built by Emperor Wen of Sui Dynasty. In the second year of Huangkai's reign in the Sui Dynasty (582), he ordered "Ziwen Zikai to be crown prince." 27-year-old Yu Wenkai, on the basis of absorbing the essence of Luoyang and Yecheng, combined with the local topography and water veins, followed the intentions of Baguazhang and Kun Gua, planned and arranged along the central axis of the capital, and adopted the method of "building a palace city". First, the Imperial City second, and Waiguo City second." The new capital was declared completed in just nine months. Emperor Wen of the Sui Dynasty granted the new capital Daxing City and the palace city Daxing Palace

Taiji Palace is located to the north of the central axis of Chang'an and is called "Xinei" compared with Daming Palace. The entire palace is 1,285 meters wide from east to west, 1,492 meters long, and covers an area of ??1.92 square kilometers. The palace is divided into three parts: the Korean area, the sleeping area, and the garden area. Along the north-south central axis of the palace city, there is Prince East Palace on the east side and Yeting Palace on the west side. The main buildings are Tai Chi Hall, Liang Yi Hall, Cheng Qing Hall, Wude Hall, Ganlu Hall and Lingyan Pavilion. Taiji Palace was built by Emperor Wen of Sui Dynasty. In the second year of Huangkai's reign in the Sui Dynasty (582), he ordered "Ziwen Zikai to be crown prince." 27-year-old Yu Wenkai, on the basis of absorbing the essence of Luoyang and Yecheng, combined with the local topography and water veins, followed the intentions of Baguazhang and Kun Gua, planned and arranged along the central axis of the capital, and adopted the method of "building a palace city". First, the Imperial City second, and Waiguo City second." The new capital was declared completed in just nine months. Emperor Wen of the Sui Dynasty granted the new capital Daxing City and the palace city Daxing Palace

Xingqing Palace is located in Xingqing Square, Chang'an, in the southeast, and is known as "Nannei". The palace is 1080 meters wide from east to west, 1250 meters long from north to south, and covers an area of ??1.34 square kilometers. Xingqing Palace consists of Xingqing Hall, Qinzheng Office Building, Calyx Incense Ash Building, Shenxiang Pavilion and Longchi. It is one of the main places where Xuanzong Li Longji and Yang Guifei lived. Among the three, Xingqing Palace is the most special, which is entirely due to the willfulness of Xuanzong Li Longji. Palaces in the past generally followed the layout of "front yard and backyard", while Xingqing Palace went in the opposite direction, with an administrative area in the north and an entertainment area in the south. Even the main hall of Xingqing Palace is located in the northwest corner of the palace, not on the central axis of the palace city. The main entrance of Xingqing Palace is the Xingqing Gate facing west, not the south gate in the traditional concept. Most of the palaces in Miyagi are architectural structures, which are complicated to build, time-consuming and labor-intensive, but more luxurious.

Li Longji had his own ideas in building Xingqing Palace. He won imperial power in only two coups. Considering the social and political situation at the time, when Li Longji moved to Xingqing Palace, he could "replace me and become my own master" and consolidate his power. In addition, he can also maintain the feelings of the other four brothers and monitor their words and deeds in real time. Behind the willfulness is shrewd calculation, which is the birth of Xingqing Palace. In the first year of Tianyou (904), Emperor Zhaozong of Tang Dynasty moved Ye Li to Luoyang by Zhu Wen.

Zhu Wen ordered "to destroy the houses of hundreds of divisions and people in Chang'an Palace", "to relocate the residents of Chang'an according to their nationality, and to evacuate their houses from the Wei River, crying for more than a month", "Chang'an has since gone to Xu Qiu". In this violent demolition, Daming Palace, Taiji Palace, and Xingqing Palace were not spared and were destroyed. In the darkness, the rise and fall of the Three Palaces is closely related to the rise and fall of the Tang Dynasty. It is both a coincidence and a fate.