The workers are farmers, draught from every common family. 300-500 thousand workers to be sent to built the wall in Qin Dynasty. Size of places? As to materials, mainly brick and stones. For such a hard and ever unparalleled construction, itself is unusual. Very popular attraction nowadays. The best parts of the Great Wall is in Beijing, such as Badaling, Simatai, Mutianyu, Jiankou, Jinshanling, etc.