The Great Wall of China stretches across thousands of kilometres and includes the famous Ming-era wall sections.
The name refers to a system of fortifications built and rebuilt by different Chinese states and dynasties, rather than one continuous wall created at one time. Qin dynasty ruler Qin Shi Huang connected earlier defensive walls in the third century BC, while the best-preserved sections were constructed mainly during the Ming dynasty between the 14th and 17th centuries.
The wall and its associated barriers, towers, trenches, and natural defenses helped control movement and protect agricultural regions from raids. Its total length is often given as more than 20,000 kilometres when all documented sections and features are counted.
A common misconception is that the Great Wall is easily visible from the Moon; it is not visible to the unaided eye from lunar distance. Popular tourist sections near Beijing include Badaling, Mutianyu, and Jinshanling.