The Great Wall is a symbol of China, and a witness to the long history of the country and a crystallization of the wisdom, strength and will of the ancient Chinese. In 1987 the Great Wall was inscribed on the World Heritage List by the United Nations Educational, Scientific and Cultural Organization.

Veteran U.S. astronaut Gene Cernan, who landed on the moon in 1972, has stated: "At Earth orbit of 160 km to 320 km high, the Great Wall of China is, indeed, visible to the naked eye."

In the Warring States Period, various states built their own walls to guard against invaders, and the walls were located in the valleys of the Yellow and Yangtze rivers. After unifying China, Emperor Shihuang of the Qin Dynasty dismantled most of the walls, and shifted the defense to the north against the Huns. The emperor sent general Meng Tian on a northern expedition, and began construction of the Great Wall. Making use of geographic conditions, the general built watchtowers and fortifications along the Yellow River and the Yinshan Mountains, and connected the extant walls of the former Yan and Zhao states in the north and the east and those built by King Zhaowang of the smaller Qin state in the west. The completed Great Wall extended from the Liaodong Peninsula in the east to Lintao of Gansu Province in the west, measuring more than 10,000 li (one li is about 0.5 km) in length. In the Han Dynasty, Emperor Wudi, who ruled from 133 BC to 87 BC, ordered generals Wei Qing and Huo Qubing to attack the Huns,  and repair the Great Wall and add new sections to it.