The Great Wall
The Great Wall (Simplified Chinese: 长城; traditional Chinese: 長城; pinyin: Chángchéng; literally "long wall") is a set of Chinese military fortifications built, destroyed and rebuilt several times and in several places between the third century BC. BC and the seventeenth century to mark and defend the northern border of China. This is the most important architectural structure ever built by man in both length, surface and mass.
Popularly, it refers as the 'Great Wall' section built during the Ming dynasty from Shanhaiguan in the territory of the city of Qinhuangdao in Hebei province to the east to reach Jiayuguan in Gansu province West. Its length can vary according to sources. According to a 1990 report, the total length of the walls would be 6 259.6 kilometers. Because of its length, it is called in Chinese "The long wall of ten thousand li" (simplified Chinese: 万里长城; traditional Chinese: 萬里長城; pinyin: Wànlǐ Chángchéng; Wade: Wan⁴li³ Ch'ang²ch'eng²), li is an ancient Chinese unit of length, and ten thousand symbolizing infinity in Chinese. This nickname can however be taken in its literal sense approximate 6 700 km by 11,632 li in his usually considered value of 576 m or 13,400 li in the present value of exactly 500 m. On average, the wall measuring 6-7 meters high and 4-5 meters wide. In April 2009, the State Administration of Cultural Heritage, who used the latest measurement technologies, review this measure and declares a length of 8 851.8 km 259.6 km including 6 walls, 359.7 km trench 2 and 232.5 km of natural barriers such as mountains or rivers. The same service was published in June 2012 an update of its study, and is now estimated at 21 196.18 km total length of the Great Wall. This new estimate takes into account the currently destroyed parts.
Since 1987, the Great Wall is a World Heritage Site by UNESCO under the number 438. In 2015, the situation is due to a sharp deterioration in the general condition of the Great Wall mainly due to climatic conditions and human activities and the need to act quickly to ensure its safeguarding.
If the term "Great Wall" is today mainly the fortifications erected during the Ming Dynasty, several walls built during previous dynasties carried this title, the borders of China evolving with time.
Traditionally, we divide the history of the construction of the Great Wall in two parts:
- one preceding the unification of the Qin Dynasty (221 BC.) during the period of Spring and Autumn and Warring States period, where the various states and kingdoms which divided China build walls land on their borders;
- the other beginning at the unification of the Qin Dynasty, when Emperor Qin Shi Huang began building a large wall of "ten thousand miles long" on the northern border.
The Great Wall is the longest man-made structure in the world.
She travels about 6700 kilometers away. Satellite studies have shown that many segments with a total length of about 1,000 kilometers were today buried underground.
Its width varies between 5 and 7 meters on average and the height between 5 and 17 meters. It is punctuated with watchtowers and bastions along its length. It is impressive on the thousands of kilometers around Beijing, the capital. It also reduced and resembles an imposing earthwork in places. It was made with stone, cement, earth, clay bricks. It was discovered recently that he was incorporated 3% of glutinous rice in a mortar which had considerably strengthened its resistance. In contrast, the same study revealed no presence of bone elements in this mortar contrary to legend, saying that its strength and whiteness was related to the