This is one of Britain's largest prehistoric stone circles, first mentioned under its current name in the work Britannia by the 17th century topographer William Camden. He described them as a "circle of stones, with a speciall one by it selfe before them. This stone the common people there by dwelling, name Long Megge, like as the rest, her daughters."
A real story behind why they are called that does not show up for another hundred years, when Celia Fiennes records that "Great Mag and her Sisters" were turned to stone for soliciting an unlawful love by enchantment. Another hundred years pass before we hear a little bit more of the story and the Cumberland historian William Hutchinson details that the place where the stones sit is a holy place and that Long Meg and her Daughters were a company of witches. They were turned to stone on the spot, because they ventured onto the holy place to profane it.
The medieval wizard Michael Scot has been connected with the site from another source, Mackenzie Walcott in 1860. The fact that there is no real solid account of the stones and that the stories are so varied and vague lends one to believe that there is actually no real distinctive local story just rather just random traditions floated about and served up as charming tales for visitors.