Great Wall

The Great Wall is a collective name that refers to a series of military fortifications built during different periods in the central plains of ancient China to resist the invasion of the nomadic tribes from the north. During the Spring and Autumn Period and the subsequent Warring States Period, all states constructed fortifications to protect themselves and linked these fortifications with walls, which became the earliest form of the Great Wall. These works were subsequently enhanced over various dynasties. The Great Wall stretches from the Yalu River in the east to Jiayuguan in the west with a total length of 8,849 km, of which the artificial wall makes up 6,259 km, and the trenches and natural walls make up 2,592 km. Its average height is 6–7 m, and its width is 4–5 m. As a magnificent project, the Great Wall is a symbol of achievement resulted from the hard work of people in the past in applying their knowledge of geological, geomorphological and geographical conditions. It is a...