China's Great Wall is known to the world as one of the seven great wonders of the world.It is located in North China.It is over 6000 kilometres in length and is 25 feet high in average.The ancient people started to built the wall in the 7th Century BC with earth,brick and stone,and joined it in the Qin Dynasty.The Great Wall was built in ancient China to keep out invaders,however,it is now regared as one of the most important tourist spots in our country or even in the whole world.Every year,it is visited by thousands of people from all over the world.