The Chang'an Site is located 5 kilometers northwest to the Xi'an City of Shaanxi Province. During the 200 years of the Western Han Dynasty (206BC-8AD), Chang'an City was the capital all along, acting as the national political, economic and cultural center.  

The construction of Chang'an was divided into three phases. In the 5^th year (202BC) of Emperor Gaozu's reign, Emperor Liu Bang renovated the Xingle Palace built in the Qin Dynasty (221-206BC), changed its name into the Changle Palace and moved the capital there. A Weiyang Palace was constructed in Chang'an in the 7^th year (200BC) of Emperor Gaozu' reign. Emperor Huidi ordered to construct the city walls right after he ascended to the throne. In the spring of the third year in his reign, Emperor Huidi ordered 140,000 young people in the 600-li city to construct the walls. In the 1^st year (104BC) of Emperor Wudi's reign in the Han Dynasty (206BC-220AD), a number of buildings were constructed in the city, including the Northern Palace, the Gui Palace, the Mingguang Palace, and the Jianzhang Palace, together with the Kunming Pool and the Shanglin Garden. Till then, the construction of various facilities in Chang'an City was complete after more than 90 years work. 

From 1956 to 1959, the Archaeology Research Institute of the Chinese Academy of Social Science carried out a comprehensive excavation at the site, providing an initial picture of the overall city arrangement, the structure of the city walls and moats, and the location of the main constructions, including the streets, palace, temples and gardens.

All city walls, 12 meters high and 12 to 16 meters wide, were constructed with tampered yellow earth. A moat measuring 8 meters wide and 3 meters deep circled around the walls. Since the walls were built after the completion of the Changle Palace and the Weiyang Palace, so the walls followed the turns of two palaces and formed the shape of Big Dipper in the south and north parts, which gave the city the name of Dipper City. According to actual measurement, the eastern wall of the city was 6000 meters long; the western one 4,900 meters, the south one 7,600 meters, and the north one 7,200 meters, covering a total area of 36 square kilometers. There were three gates open on each side of the wall, with three gateways on each gate. Altogether there were 12 gates with 36 gateways, right in line with the structural style recorded in the historical writings.

Each gate was connected to the streets, ensuring a convenient traffic. The city had eight main avenues, with the longest one of 5,500 meters long and 45 meters wide. Each street was divided into three ways, with the middle one only used by the emperor himself and the side ones for ordinary citizens. Various kinds of trees, such as pagoda tree, elm, pine, and cypress, grew along both sides of the streets, which divided the city into regular-shaped residential and downtown areas. During its most flourishing period, Chang'an City had a population of 240,000 of 88,000 households. It was the first large-scale and densely populated city in Chinese history.

Palaces, residences for nobles, official residences, and temples were the main constructions inside the city. The Changle Palace was built in the southeast of the city, hence it was also known as the East Palace. In the early Han Dynasty, emperors used the palace to receive officials and Emperor Huidi changed it into the residential palace for the queen mother. Surrounded by walls with a perimeter of 10,000 meters, the palace took an irregular shape and covered an area of 6 square kilometers, occupying nearly 1/6 of the total city area. Inside the palace were a front hall, the Linhua Hall, the Changxin Hall, the Changqiu Hall, the Yongshou Hall, the Shenxian Hall, the Yongchang Hall, and the Bell Room.

Built in the southwest of the city, the Weiyang Palace was also known as the West Palace, where the emperor met with officials. Covering an area of 5 square kilometers, the palace had a square shape, with walls built on four sides, of which the east and the west walls were 2150 meters long each, and the south and the north ones 2250 long each. A gate was open on each of the four sides. The east and north gates each had a watchtower, and the east one was open for the feudal princes who wanted to meet with the emperor while the north one was for ordinary people. Inside the palace were over 40 halls and pavilions, including the front hall, Xuanshi Hall, Wenshi Hall, Qingliang Hall, Qilin Hall, Jinhua Hall, and Chengming Hall, etc. Once occupied by emperors of 7 dynasties, namely the Western Han, Western Jin, Former Zhao, pre-Qin, post-Qin, Western Wei, and Northern Zhou successively, the palace has become the most famous one in Chinese history. According to survey, the front hall, situated in the center of the palace, had a foundation site of 350 meters long from south to north, 200 meters wide from east to west, and 15 meters at the highest point which caused by the Dragon-Head Hill. 

Between the Changle Palace and the Weiyang Palace was a site of arsenals. Taking the shape of a square, the site was surrounded by walls on four sides, with the east and west walls of 320 meters long each and the south and north ones 880 meters each. Inside the walls were 7 arsenals, each divided into 4 storerooms. Shelves, originally orderly arranged in the rooms, were rotten and gradually disappeared through the years.

Built in the Shanglin Garden, the Jianzhang Palace comprised a number of small palaces and was known to have one thousand gates and ten thousand rooms. Its front hall was higher than that of the Weiyang Palace. A watchtower of 20 zhang was built in the east of the palace, with its remains still extant now. In the north was a Taiye Pool, on which were several islands, including the Penglai Island, the Fangzhang Island, and the Leizhou Island. These islands, with pavilions strewn at random, formed a fascinating landscape like a fairyland. In the south of the palace were several buildings, including the Shenming Building and Jinggan Building. The whole Shanglin Garden had a perimeter of over 100 kilometers.

Residential areas were located in the north part of the city. The city streets divided the residential areas into 160 regularly measured communities. A few residences of nobles were built near the north gate of the Weiyang Palace and gained their name as north gate mansions. Located in the northwest of the city was the famous Nine Markets of Chang'an.

After Wang Mang usurped the power, he ordered a large-scale construction in the south suburb of Chang'an City. The construction of Biyong, Mingtang, Lingtai and nine temples was designed according to social etiquette. Archeological finds have proved that these buildings were designed in line with traditional Confucian etiquette and the theory of Yin & Yang and Five Elements, which was popular in the Han Dynasty. The construction style of these buildings reflects the then popular ideology.