The Great Wall of China, also known as the Great Chinese Wall or the Great Wall of 10,000 Li¹, is the longest structure ever created by humans in China.
The Great Wall of China is considered one of the Seven Wonders of the World. In 1987, it was included in the UNESCO World Heritage List.
Length
The Great Wall of China is not continuously long, but rather a collection of short walls that follow the shape of the northern mountains of China. On April 18, 2009, after accurate investigation by the government of the People's Republic of China, it was announced that the giant wall constructed during the Ming Dynasty is 8,851 km long.
According to historical records, the term "changcheng" (长城, "great wall" or "long wall") was only known after the long wall was built by the Ming Dynasty. Before that, the term was not found. The term "Great Wall of China" in Mandarin is "wanli changcheng," meaning "a wall that is 10 thousand li long." This term is officially used nowadays.
In 2009, the Surveying and Mapping Authority and the Cultural Heritage Administration of the People's Republic of China conducted research to recalculate the length of the Great Wall of China. The research results showed that the Great Wall of China is longer than the currently known range. According to measurements, the total length of the wall reaches 8,850 km. The project has also discovered other parts of the wall that are 359 km long, ditches that are 2,232 km long, as well as natural barriers such as hills and rivers that are 2,232 km long. The average span of the Great Wall of China is 5,000 km, generally quoted from various historical records.
From space, the Great Wall of China is often mentioned as one of the man-made structures that can be seen with the naked eye. However, after investigations conducted by astronauts, this perception is not true. From low orbit, man-made structures such as roads, ships, cities, and others can indeed be seen, but when passing through the Earth's orbit at an altitude of tens of thousands of feet, no objects on the Earth's surface can be seen, including the Great Wall of China.
This is supported by NASA's statement: "The Great Wall can barely be seen from the Shuttle, so it would not be possible to see it from the moon with the naked eye." The first Chinese astronaut launched into space in 2004, Yang Liwei, also stated that he could not see the structure. The perception of the giant wall being visible from space has become a myth, even written in school textbooks in China.
The earliest evidence comes from the writings of an English antique collector named William Stukeley in 1754, who compared the Great Wall of China to Hadrian's Wall in England, stating that Hadrian's Wall in England can only be surpassed by the Great Wall of China, which is an important structure in the world and could possibly be seen from the moon. Richard Halliburton's book, "Second Book of Marvels," published in 1938, further convinced people that the giant wall could be seen from space.