Jinshanling section of the Great Wall is about 133 kilometers (82. 5 miles) away from downtown Beijing and stretches from Miyun County of Beijing, to Luanping County of Hebei Province. The name came from two towers-Greater Jinshan Tower and Lesser Jinshan Tower on the Great Wall in this region. It was said that three thousand soldiers under Ming General Qi Jiguang (1528-1587) were all natives of Jiangsu and Zhejiang provinces. They built two watch towers and named them after Great Jinshan Island and Lesser Jinshan Island in Zhenjiang, their homeland, just to show their sentimental feelings toward their hometown.
Jinshanling Great Wall has two unique features: first, the density of the watch towers; the Jinshanling Section of the Great Wall is 13 kilometers (8 miles) long but with 90 watch towers. The general interval of the watch tower on the wall is about 100 meters, but in some places with more complex terrain, the interval is only 50 to 60 meters. Such density of the watch towers is really rarely seen on the entire length of the Great Wall.
Since the terrain in the Jinshanling area is so complex, its defense project was especially strong. Many beacon towers were built on every vantage point north of the Great Wall to control the high vantage points and protect the main Wall. Thus the defense of the Great Wall was further enhanced, forming a special feature of the Great Wall at Jinshanling.
The other feature is the“Barrier Wall”. The Barrier Wall was built on the top inside the Great Wall, vertical and parallel to the battlements. The Barrier Wall is 2.5 miters high with peep holes and arrow holes in it. It served as the second barrier whenever the enemy climbed up the Great Wall.