(BADALING)

During the Han Dynasty (206BC-220AD) which followed the Qin (221BC-206BC), in order to protect the farming areas from the harassment of nomadic people, the Han emperors constructed military defensive works like castles, battlements, fortifications and beacon towers along the wall which started in Liaodong in the east and ran on to Yanze (present-day Lop Nur in Xinjiang), Fengsui , until the western part of Xinjing with a total length over 10,000 kilometers. The construction of the Great Wall went on for over two thousand years through various historical periods including Northern Wei, Northern Qi, Eastern Wei, Nothern Zhou, Sui, Liao, Kin and particularly during the Ming Dyanasty whose rule lasted over two hundred years. It was then over 6,300 kilometers from Yalu River in the east to Jiayuguan in the west and became known as the Great Wall of Ten Thousand Li. Nine garrison areas were set up to carry out effective control and repairs of th e entire wall. They were Liaoding, Jizhou, Xuanfu, Datong, Shanxi, Yansui, Ningxia, Guyuan and Gansu, forming a complete defensive system with walls, passes, castles, strategic platforms and beacon towers. Most part of the Great Wall we see today were constructed in this period. Investigations show that the walls spanning Heilongjiang, Jilin, Liaoning, Hebei, Beijing, Tianjin, Shanxi, Inner Mongolia, Henan, Shaanxi, Shangdong, Hubei, Hunan, Ningxia, Gansu, Xinjing, etc. during various add up to over 50,000 kilometers.

(MUTIANYU)

Through the dynasties, the construction of the Great Wall followed the principal of using local materials where possible. Earth and stones were the most common, other materials were also possible according to natural conditions. The wall, the main body of the Great Wall,was rammed earth in the early period; later stones, in certain sections, planks and boards according to geological characteristics. Natural terrain was also taken advantage of to make up part of the wall. Even today materials other than earth and stone are still discernable. The walls of the Qin and Han dynasties were of rammed earth or rocks while taking advantage of steep mountain ridges and precipices where possible.
In grasslands and deserts subjected to wind erosion, the walls were built wtih unburnt bricks or layers of reeds and tamarisk twigs filled with sand and crushed stones like the Great Wall at Yumenguan in Gansu Province. The Kin Dynasty wall in the Inner Mongolian plateau where stone was scarce was rammed earth and unburnt bricks. In the Ming Dynasty a wall of large slabs of granite and bricks filled in with crushed stones and earth was erected over the contours of mountain ridges like the section between Juyongguan and Badaling which saved material and labour power and was easy to build.

(Rouyuan Tower)

Yanmenguan in Shanhaiguan in Hebei to Yanmenguan in Shanxi was bricks filled in with earth and crushed stone. Defensive works like passes, castles, strategic platforms and beacon towers were built along the Great Wall according to the geological importance of the section and to serve the military needs of garrion, grain and weapon storage, defence, and the transmission of military information.
The Great Wll in history, a product of cultural clashes between the agricultural and nomadic peoples, played an important role in propelling the Central Plain's economic development and cultrual progress, stabilizing and unifying a multi-national country, and guaranteeing the passage of the "Silk Road" which linked ancient China with the West. The Great Wall today may have lost its former functions, it has nevertheless become a monument of the ancient civilization of the Chinese nation. It is the fruit of concerned labour of various nationalities. Like the pyramids of Egypt, the arena in Roman antiquity and the leaning tower of Pisa, it is one of the wonders of the world, symbolizing the wit and spirit of the Chinese nation.