Both sides of the north-south central axis of Chang 'an City are symmetrical. Wannian county is located in the eastern half, with an eastern city; Chang 'an County is located in the western half, with a western city. Most of the 54th Square in the east half and the 55th Square in the west half are symmetrical, which is slightly changed due to the renovation of Xingqing Palace and Daming Palace. The streets of Chang 'an are arranged in the north-south and east-west directions, perpendicular to each other, straight and upright, carefree and open-minded. There are 1 1 streets in the north and south columns and 14 streets in the east and west columns, which divide the outer Guo Cheng into 109 rectangular squares and two cities in the east and west, each occupying two squares. There are 220 lines in Dongcheng (some people say 120 line), and in Xicheng, "the shops in the city are also like Dongcheng". Xicheng is the commercial center of Chang 'an and the economic activity center of Chang 'an. There are drains on both sides of the street, and locust elms are planted. The avenue is straight, the trees are shaded, and the city is very spectacular. Bai Juyi told Zhang Ji's poem that "all the way to Qinghuai Street, eight or nine squares apart" reflects this situation. The structure of the square is closed, each square has a wall, and the doors of the house are all in the square. Many Persian merchants are engaged in jewelry industry, and most of them live in Xicheng.

One million people in Chang 'an need a lot of supplies. Businessmen and foreign businessmen from all over the country gathered in Beijing to promote trade and make Chang 'an East-West City prosperous. Only in the history books can we see that the industries in the two cities are iron, meat, pen, coat, fur, medicine, weighing, silk, bran, fish, restaurants, silk, clothing stores and consignment shops. In the late Tang Dynasty, the prosperity of the two cities reached its peak. Large and small businesses have developed around these two cities and the city gates. For example, Chongren Square is "a street that meets (fú cê u), and then leans (exceeds) towards the two cities. It is noisy day and night, and the lights are endless. There are many squares in Beijing, which are incomparable. " This shows that after the middle Tang Dynasty, the industrial and commercial development of Chang 'an City broke through the geographical scope of the two cities and the restriction of night ban in time.

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