The Great Wall of China is a series of stone and earthen fortifications in northern China , built originally to protect the northern borders of the Chinese Empire against intrusions by various nomadic groups such as the Xiongnu from the north and rebuilt and maintained between the 5th century BC and the 16th century.
Since the 5th century BC, several walls have been built that were referred to as the Great Wall. One of the most famous is the wall built between 220-206 BC by the first Emperor of China, Qin Shi Huang. Little of that wall remains; the majority of the existing wall was built during the Ming Dynasty.
The Great Wall stretches from Shanhaiguan in the east to Lop Nur in the west, along an arc that roughly delineates the southern edge of Inner Mongolia. The most comprehensive archaeological survey, using advanced technologies, has recently concluded that the entire Great Wall, with all of its branches, stretches for 8,851.8 km (5,500.3 mi). This is made up of 6,259.6 km (3,889.5 mi) of sections of actual wall, 359.7 km (223.5 mi) of trenches and 2,232.5 km (1,387.2 mi) of natural defensive barriers such as hills and rivers.
In c. 220 B.C., under Qin Shi Huang, sections of earlier fortifications were joined together to form a united defence system against invasions from the north. Construction continued up to the Ming dynasty (1368?C1644), when the Great Wall became the world's largest military structure. Its historic and strategic importance is matched only by its architectural significance.
Known to the Chinese as the 'Long Wall of Ten Thousand Li', the formidable defensive structures built to ward off invasion of the Celestial Empire by barbarians is called the Great Wall or the Wall of China by Europeans. The principle of these extraordinary fortifications goes back to the Chunqiu period (722-481 BC) and to the Warring States period (453-221 BC).