Badaling is located at Yanqing County, more than 70 kilometers northwest from the center of Beijing City. It is a mountain pass of the Jundu Mountain. Badaling is at the highest point of north end of the Guan Gou gorge, in which the Juyongguan Pass lies. In the history, the function of Badaling was to protect the Juyongguan Pass. Along with Guan Gou gorge, there are several interests and historic sites. Badaling is a rare ancient military defense project. The elevation of it is about 1,000 meters. Badaling Great Wall occupies a commanding and strategic position. It is called "Bada" as it stretches in all directions. Stretching out for 4,770m among the rolling mountains, Badaling section of Great Wall is dotted with 19 strategically located watchtowers, which were used to protect the capital against attack in ancient times, bringing Badaling the name of "key to the north gate."
Badaling Great wall was built in the 18th year of the Ming Hong Zhi Reign (1505AD). The wall, built with high stone slabs on the outside, is 7.8 meters high on the average, some even reaches 8.4 meters. The base of the wall was built with more than 2000 large rectangular slab of granite stones. It is about 6.5 meters wide on the average at its base and 5.7 meters wide on the average on the ramparts. The wall is wide enough for five horses to gallop abreast and ten people to advance shoulder to shoulder. The outside of the wall is called rampart wall. The rampart wall was built with bricks 1.7 meters high. Built for the purpose of defense, there are holes on the tip of the wall called watch-hole, and peepholes under the wall called embrasures. Inside of the wall, there are low walls with one meter high called parapets, which can be used as railings. There is a scroll door not far from the inside wall, with is a stone ladder for climbing up and down.
Following unification of the separate kingdoms under Qin Shihuang (First Emperor of the Qin) in 221 B.C., the existing fortifications were linked up and extended. As the crow flies, this is about 2,000 kilometers (1243 miles). However, the wall wound over high mountain ranges and valleys, and at some strategic passes, doubled back or redoubled. Therefore, its total length is actually more than 6,700 kilometers (4163 miles).
The Qin Great Wall was located to the north of the present wall. The construction of such an immense engineering project over such difficult terrain was an extraordinary feat for ancient times. Qin Shihuang employed a work force of almost a million, composed of soldiers, peasants and convicts, representing a fifth of the whole labor force of the country at that time.
Badaling, the essence of the Great Wall, in 1987, was listed as the "World Cultural Heritage" by UN. The Great Wall was not only an immense defensive edifice, but also served as an important path of communication through northern China. It also serves as a valuable museum of military life and battle conditions in ancient China. Such is its extraordinary world-wide fame that even in the depths of winter or the fiercest heat of summer, the stream of tourists never stops.