One of the most popular spatial myths is that the Great Wall is the only man that can be seen from space. Well, not true. The reality is you cannot easily see the Great Wall from low Earth orbit to the naked eye. And rightly the Apollo astronauts could not see it from the moon, despite the urban legend has spread widely.
Neither the first Chinese astronaut Yang Liwei in 2003, and the Canadian Chris Hadfield in 2012-2013, could see it, the Great Wall of China is too narrow and blends in with the landscape.
The image above is the first picture of the Great Wall verifiable from space, which was obtained by U.S. astronaut Leroy Chiao from a window of the International Space Station in 2004. Photographed a region of Inner Mongolia, but to do Chiao needed to use the zoom on a digital camera and still was not sure I photographed.
So what structures are visible from orbit? Astronauts on the International Space Station have said that (without taking into account the cities at night) the ancient pyramids of Giza are relatively easy to see from the station, but the easiest to see are long roads or bridges.
At first glance, you can see and recognize some artificial structures from space, but the Great Wall of China is not one of them.