Great Wall of China

The Great Wall of China is a system of fortifications and defensive barriers located in northern China. It is not a single continuous wall, but rather an interconnected series of walls, moats, watchtowers, garrison stations, and gates that different dynasties built over widely separated periods.

A national survey spanning several years, published by China's cultural heritage authority in 2012, calculated that the total length of the entire system—combining all the various dynasties—is approximately 21,196 kilometers. The largest portion still standing today comes from the Ming dynasty, estimated at roughly 8,850 kilometers.

History of construction

Defensive walls in the north were built from early periods under different dynasties. The Ming dynasty (14th–17th centuries) rebuilt and expanded the wall using stone and brick, resulting in the famous appearance visible today near Beijing. The purpose of construction was to regulate border traffic, protect trade routes, and defend against cavalry raids from the eastern and central Asian regions.

Measurements and counting methods

Length figures vary depending on what is counted. The 2012 survey included sections that have now collapsed, where only foundations remain, and natural barriers used for defense. The figure of over 21,000 kilometers thus represents the combined length of all documented sections, not a single continuous line. Britannica notes that roughly 70 percent of the total length consists of actual built wall, while the remainder comprises barriers or moats.

The survey also catalogued tens of thousands of heritage sites associated with the system, though some lack physical remains and are known only through documents and local records.

State of preservation and protection

UNESCO inscribed the Great Wall on the World Heritage List in 1987 under number 438. Official reports and press accounts have noted that large sections have deteriorated due to natural causes (frost, rain, wind erosion) and human activity such as unregulated construction and uncontrolled quarrying.

Sections prepared for tourism—such as those near Beijing—represent only a small portion of the system and are generally restored. As a result, the famous appearance shown in photographs does not reflect the condition of most other sections spread across distant deserts and mountains.