< ">The Great Wall of China is a series of fortresses of stone, brick, tamped earth, wood and other materials, usually along an east-west line across the northern border of China’s historic built partly to protect the Chinese Empire, or made his prototypical States against attacks from various nomadic groups and military incursions by various armed forces or people. Several walls were already in the 7th Century BC, built This, and later joined forces and made bigger, stronger and more uniform than are now jointly known as the Great Wall Especially famous is the wall built between 220. -206 BC by the first Emperor of China, Qin Shi Huang. Little remains of this wall. Since then, the Great Wall was rebuilt and off, maintained, improved, the majority of the existing wall was reconstructed during the Ming Dynasty.Other purposes have included the Great Wall, the border controls, so that the imposition of duties on goods along the Silk Road, regulation or promotion of trade and control of immigration and emigration transported. In addition, the defensive features of the Great Wall through the construction of watch towers, crew barracks, garrison stations, signaling capabilities by means of smoke or fire, and reinforces the fact that the route of the Great Wall also served as a transportation corridor.The Great Wall stretches from Shanhaiguan in the east to Lop Lake in the west, along an arc that roughly describes the southern edge of Inner Mongolia. The most extensive archaeological investigation, using advanced technologies, has found that all the walls measure 8,851.8 km (5,500.3 mi). This consists of 6,259.6 km (3,889.5 mi) Parts of the actual wall, made 359.7 km (223.5 km) of trenches and 2,232.5 kilometers (1,387.2 mi) of natural defensive barriers such as mountains and rivers.