The Great Wall was the greatest manmade military defense structure in ancient China. Its construction started during Ancient Spring and Autumn Period and the Warring Stated Period (770-221 B.C.) At that time, walls were built by some warring states to protect their own territories. In 221 B.C., Qin Shihuang, who became the first emperor of a unified China, linked the separate walls into a ¡°ten-thousand-li wall¡± to defend against invaders from the North. From then on, the Great Wall was continuously extended and repaired by following dynasties. Most of wall has deteriorated badly; at present, the best preserved is the wall built in the Ming Dynasty (1368-1644)).
The Ming Dynasty Wall stretches from the Yalu River in Liaoning Province in the east to Jiayuguan Pass in Gansu Province in the west, a length of more than 6,000 kilometers. It runs through 5 provinces, 2 autonomous regions and 2 municipalities in the Northern China.
The Great Wall at Badaling is the best representative section of the Great Wall. It is more than 7 meters high and 5 meters wide. It was the strategic point of Juyongguan Pass in ancient times. Many other fortresses and beacon towers were constructed at the strategic points.
This section of the Great Wall has drawn great attention from the Chinese government since the foundation of P.R. China. It was designated a major historical site under state protection in 1961. The Great Wall was listed as "a World Cultural Heritage" by the UNESCO in 1987.
The Great Wall at Badaling is preserved as a historical monument and has become one of the most popular tourist attractions in the world.