Compared with other ancient capitals, Chang'an has been an imperial capital since ancient times. First, it was built earliest. Second, it was built by 13 dynasties. Third, it was built by the longest time, up to 1062, while Beijing was only 600 years old. Fourth, it was the first metropolis in Chinese history to reach one million people and implement urban construction and management at the earliest time. At the same time, Xi'an, as well as Athens, Cairo, Rome and Istanbul, is one of the world's five famous ancient capitals. The ancient city of Xi'an, the witness of history!