The Great Wall The Great Wall is a great miracle in the world. Nowaday, thounsands of people visit it every year. On high season, a few of famous sights are crowded by a fleet of tourists.The histoy of Chinese people built the Great wall is long ,dating back from the Warring State period. Historically, Chinese had built about 20 walls. Among those walls , the wall ,built in Ming Dynasty ,is the longest one which is up to 6700km.At that time,the Chinese technology was the leader of the world so the structure of Ming` wall was the most complex one. The purpose of building Ming`s wall was to prevent the invasion of nomads who lived in the north of China