Great Wall of China

The Great Wall
Map of all the wall constructions
General information
Type	Fortification
Country	China
Coordinates	40.67693°N 117.23193°ECoordinates: 40.67693°N 117.23193°E
Construction started	7th century BC
Technical details
Size	21,196 km (13,171 mi)[1]
UNESCO World Heritage Site
Official name: The Great Wall
Type:	Cultural
Criteria:	i, ii, iii, iv, vi
Designated:	1987 (11th session)
Reference #:	438
State Party:	China
Region:	Asia-Pacific

Great Wall of China

The Great Wall of China is a series of fortifications made of stone, brick, tamped earth, wood, and other materials, generally 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. Several walls were being built as early as the 7th century BC;^[3] these, later joined together and made bigger, stronger, and unified are now collectively referred to as the Great Wall.^[4] Especially famous is the wall built between 220–206 BC by the first Emperor of China, Qin Shi Huang. Little of that wall remains. Since then, the Great Wall has on and off been rebuilt, maintained, and enhanced; the majority of the existing wall was reconstructed during the Ming Dynasty. 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. Furthermore, the defensive characteristics of the Great Wall were enhanced by the construction of watch towers, troop barracks, garrison stations, signaling capabilities through the means of smoke or fire, and the fact that the path 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 delineates the southern edge of Inner Mongolia. A comprehensive archaeological survey, using advanced technologies, has concluded that the Ming walls measure 8,850 km (5,500 mi).^[5] This is made up of 6,259 km (3,889 mi) sections of actual wall, 359 km (223 mi) of trenches and 2,232 km (1,387 mi) of natural defensive barriers such as hills and rivers.^[5] Another archaeological survey found that the entire wall with all of its branches measure out to be 21,196 km (13,171 mi).^[6]
HistoryGreat Wall of the Qin Dynasty

Great Wall of the Han Dynasty

Great Wall of the Ming Dynasty

The Chinese were already familiar with the techniques of wall-building by the time of the Spring and Autumn Period between the 8th and 5th centuries BCE^[7] During this time and the subsequent Warring States Period, the states of Qin, Wei, Zhao, Qi, Yan and Zhongshan^[8][9] all constructed extensive fortifications to defend their own borders. Built to withstand the attack of small arms such as swords and spears, these walls were made mostly by stamping earth and gravel between board frames.
Qin Shi Huang conquered all opposing states and unified China in 221 BCE, establishing the Qin Dynasty. Intending to impose centralized rule and prevent the resurgence of feudal lords, he ordered the destruction of the wall sections that divided his empire along the former state borders. To protect the empire against intrusions by the Xiongnu people from the north, he ordered the building of a new wall to connect the remaining fortifications along the empire's new northern frontier. Transporting the large quantity of materials required for construction was difficult, so builders always tried to use local resources. Stones from the mountains were used over mountain ranges, while rammed earth was used for construction in the plains. There are no surviving historical records indicating the exact length and course of the Qin Dynasty walls. Most of the ancient walls have eroded away over the centuries, and very few sections remain today. The human cost of the construction is unknown, but it has been estimated by some authors that hundreds of thousands,^[10] if not up to a million, workers died building the Qin wall.^[11][12] Later, the Han,^[13] Sui, and Northern dynasties all repaired, rebuilt, or expanded sections of the Great Wall at great cost to defend themselves against northern invaders.^[14] The Tang and Song Dynasties did not build any walls in the region.^[14] The Liao, Jin, and Yuan dynasties, who ruled Northern China throughout most of the 10-13th centuries, had their original power bases north of the Great Wall proper. Accordingly, they would have no need throughout most of their history to build a wall along this line. The Liao carried out limited repair of the Great Wall in a few areas,^[15] however the Jin did construct defensive walls in the 12th century, but those were located much to the north of the Great Wall as we know it, within today's Inner and Outer Mongolia.^[14][16]