They are shapeshifters and there are a number of legends, and versions of the same legend, as a result of centuries of oral tradition. They appear as guardians of the pathways into the earth and of the “limit” frontiers where it was believed that the supernatural could manifest itself. Mouras encantadas are magical maidens who guard castles, caves, bridges, wells, rivers, and treasures. […]
Almost every Portuguese or Galician town has a tale of a Moura Encantada. The lore of the mouros encantados is used to find prehistoric monuments and was for some time used in the 19th century as the main method to locate Lusitanian archaeological “monuments”, as Martins Sarmento viewed these as a kind of folk memory that was erased with Christianization.
Like the Mairu of Basque mythology built dolmens or harrespil, the mouras are builders of ancient monuments.
Source: Enchanted Moura – Wikipedia