All sections of the Great Wall of China together measure about 21,196 kilometers (roughly 13,171 miles), according to China’s official survey. That total counts every wall built by successive dynasties, not one continuous line.
The best-known stretches, such as Badaling and Jinshanling near Beijing, were built by the Ming dynasty (1368–1644). The wall system runs from Liaodong in the east to Lop Lake in the west.
Source: Wikipedia, Great Wall of China