Mutianyu Section of the Great Wall avtor Michael McDonough

Mutianyu (Chinese: 慕田峪; pinyin: Mùtiányù) is a section of the Great Wall of China located in Huairou County 70 km northeast of Beijing. The Mutianyu section of the Great Wall is connected with Jiankou in the west and Lianhuachi in the east. As one of the best-preserved parts of the Great Wall, the Mutianyu section of the Great Wall used to serve as the northern barrier defending the capital and the imperial tombs. First built in the mid-6th century during the Northern Qi, Mutianyu Great Wall is older than the Badaling section of the Great Wall. In the Ming dynasty, under the supervision of General Xu Da, construction of the present wall began on the foundation of the wall of Northern Qi. In 1404, a pass was built in the wall. 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 700–85000 metres high and the top is 4–5 metres wide. Compared with other sections of Great Wall, Mutianyu Great Wall possesses unique characteristics in its construction. Watchtowers are densely placed along this section of the Great Wall - 22 watchtowers on this 2,250-metre-long stretch. 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. The Mutianyu Pass consists of 3 watchtowers, one big in the centre 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. -Wikipedia