The Great Wall of China is a series of stone and earthen fortifications in northern China, built originally to protect the northern borders of the Chinese Empire against intrusions by various nomadic groups. Several walls have been built since the 5th century BC that are referred to collectively as the Great Wall, which has been rebuilt and maintained from the 5th century BC through the 16th century.

The Great Wall stretches from Shanhaiguan in the east, to Lop Lake in the west, along an arc that roughly delineates the southern edge of Inner Mongolia. The most comprehensive archaeological survey, using advanced technologies, has concluded that all the walls measure 8,851.8 km. This is made up of 6,259.6 km sections of actual wall, 359.7 km of trenches and 2,232.5 km of natural defensive barriers such as hills and rivers.

Simatai, a section of the Great Wall of China located in the north of Miyun County, 120 km north-east of Beijing, holds the access to Gubeikou, a strategic pass in the eastern part of the Great Wall. Simatai Great Wall is 5.4 km long with 35 beacon towers. This section of the Great Wall incorporated the different characteristics of each section of the Great Wall.