It is hard to know the person who proposed the idea to built Great Wall. In fact, the construction of the wall has a long history. I would like to tell something about the Wall at the very begining. It was in the Spring and Autumn, Waring States perios, 7th Century BC. Among the vassal states, Chu is the first to built the Wall, called Fang Cheng (Square City), later Qi State also built such walls within its territory. The idea of those fortification cames from signal fire turrets, castles or fortress. To protet themselves from the intrusion of the Huns, other states built their own walls. All the walls are seperate. So, when the Qin united the country, thw seperated walls had to connected together. The project began 10 years after Ying Zheng ascent the throne. Qin built the wall for 15 years. To protect itself from Mongolian, Ming Dynasty spent 277 years on the construction of the Great Wall.