Any massive undertaking will have legends grow up around it, and the Great Wall of China is no exception. Originally built as a series of massive defensive fortifications meant to exclude nomadic peoples to the northwest, perhaps the most famous myth about it is thaht it can be seen from space. There are a couple, though, that are far more interesting.
Among the most macabre of such legends is of the kind that grows up around any large structure, from the Hoover Dam to the Empire State Building to the Pyramids of Giza: the edifice is also a tomb. Some will contend that the mortar for the stones of the Great Wall was made from human flesh, blood and bone (it was not). Others will assert that the bodies of builders who died on the job are buried where they fell, and those who fled from the building were interred within it while yet living; such sources as report it are notably scanty of reference to verifiable evidence that the bones of the fallen lie within the Wall. Also, the void decaying bodies would leave in the structure would weaken it, and the architects would not have been eager to have the defenisve structure made less effective for that reason. Thus, while people did die in constructing the Great Wall, they do not lie therein.
Again, though, people died at work on the Wall, as working conditions were poor. Often, conscript labor was employed, either of convicts or of levies. One such is held to have led to the unmaking of a portion of the Wall.
The story is that of Meng Jiangnu, whose husband had been forced to work on the Great Wall and died while doing so. (Some versions assert he was entombed in the Wall--which, again, is not true.) In the legend, she travels with much hardship to the place where he had been taken to work, and so mighty were her tears upon learning of his death that the section of the Wall where he had worked fell; she collected his remains to offer them proper burial, after which the section of Wall was rebuilt. Different versions deploy different secondary details such as other marriage ideas, but the core of the story is the love of Meng Jiangju for her husband--a charming, if implausible, story.