The Mutianyu Great Wall lies aboout 70 km northeast of Beijing in Huairou County. It is 2250 meters long with 22 watchtowers, but only 1700 meters with 14 watchtowers is open to the public. It was strategic pass built in the Ming danasty. 

Two unique features of Mutianyu section are : The "double sides battlements" and the"branch walls". Other parts of the great wall have battlements only on the outer side and parapets on the inner side, but here both inner and outer parapets are crenellated with merlons, so that shot could be fired at the enemy at both sides.  At some places in this section,  the mountain ridge branches out either inside or outside the main wall, anothor section piece of wall was built on this mountain. The protrusions wall for several meters or several dozon meters long on which watch towers were built. This part of the wall is known as "Branch Wall", which was on the mountain ridge but connected with the main wall. The branch wall could control the high vantage points to protect the main part of the Wall. The Branch Walls really played an important role in the past.

The Great Wall of the Mutianyu section was opened to the public in 1986. The section is accessible by cable cars from below.  If you have the time it will be particularly nice to walk up and down.