Great Wall of China indows 8.1/10 Theme and Wallpapers, The Great Wall of China is the longest in the world and has a main-line length of 3460km plus 3530kms of branches and spurs as per the Guinness World Records. Its height varies from 4.5 to 12m 15 to 39ft and it is up to 9.8m 32ft thick. Another archaeological survey found that the entire wall with all of its branches measure out to be 21,196 km. The Great Wall was built along an east-to-west line across the historical northern borders of China in part to protect the Chinese Empire or its prototypical states against intrusions by various nomadic groups or military incursions by various warlike peoples or forces. Other purposes of the Great Wall have included border controls, allowing the imposition of duties on goods transported along the Silk Road, regulation or encouragement of trade and the control of immigration and emigration. Download free Great Wall of China desktop backgrounds and pictures for Windows, Linux and Androind.