Huge and Invisible

The myth that the Great Wall of China is the only man-made object visible from the moon started in 1754 when English historian William Stukeley wrote that it made "a considerable figure upon the terrestrial globe, and may be discerned at the moon"

Turns out Stukeley was the mid eighteenth century version of Wikipedia. Not necessarily everything he said was fact-checked.

The wall is on average about 7 metres wide. From the moon, that is approximately the same width as a human hair viewed from 3.2 kilometres away. You'd have to have pretty good eyesight to pick that out.

Not only is it not visible from the moon, its impossible to see with the naked eye from low Earth orbit. Because it's made from material not that different in colour from the rocks around it, even with a camera and telephoto lens astronauts on the ISS had trouble locating it.

This shot hasn't been 'shopped to remove the throngs of tourists, by the way. This is a section not open to the public, but within viewing distance of the main 'tourist' wall at Badaling near Beijing