Mutianyu Great Wall was first built in the mid-6th century during the Northern Qi, making it older than the Badaling section. In 1569, the Mutianyu Great Wall was rebuilt and till today most parts of it are well preserved. The Mutianyu Great Wall has the largest construction scale and best quality among all sections of Great Wall.
Built mainly with granite, the wall is 7-8 meters high and the top is 4-5 meters wide. Compared with other sections of Great Wall, Mutianyu Great Wall possesses unique characteristics in its construction:
1. Watchtowers are densely placed along this section of the Great Wall - 22 watchtowers on this 2,250-meter-long stretch.
2. Both the outer and inner parapets are crenelated with merlons, so that shots could be fired at the enemy on both sides - a feature very rare on other parts of the Great Wall.
3. The Mutianyu Pass consists of 3 watchtowers, one big in the center and two smaller on both sides. Standing on the same terrace, the three watchtowers are connected to each other inside and compose a rarely seen structure among all sections of Great Wall.
http://www.topchinatravel.com/china-attractions/mutianyu-great-wall.htm
360-degree panorama photography by yunzeng liu