Measuring about 13,170 miles (21,196 kilometers) long, the Great Wall is no doubt the longest manmade project on the earth. It was once widely believed that it can be seen from the space. Many astronauts have verified this saying and taken photos as evidence. Some medium even reported with affected seriousness, "The biggest building the astronauts could see from the space is the wall, which looks very much like a black worm." Consequently, this statement has gone deep into people's minds and become an honor that Chinese people enjoyed for years.