The Mysterious Maiden Mélusine
Luxembourg has a rich folklore tradition, and the tale of Mélusine the mermaid is perhaps the nation's most famous myth. Legend says that imprisoned within the rock that helped form Luxembourg City's tremendous defenses is a beautiful maiden named Mélusine. She passes the time by knitting, but she manages only one stitch each year -- and it's a very good thing she's so slow. You see, should she finish her knitting before she's released, all of Luxembourg and its people will vanish into the rock with her!
Mélusine was imprisoned after Siegfried married her without knowing that she was really a mermaid. At first, she kept her secret by reverting to her natural state only on Saturday, a day she told her husband that was reserved for her personal privacy. But when his curiosity got the better of him and he peeked, she vanished into the rock.
Once every 7 years, Mélusine returns, either as a serpent with a golden key in its mouth or as a beautiful woman. All it will take to win her freedom is for some brave soul to kiss the womanly vision or take the key from the serpent's mouth. That brave soul has yet to appear, and in the meantime all of Luxembourg (or at least that part of Luxembourg that believes in the legend) prays for her to drop a stitch or two so that whatever she's knitting will take a very long time to complete!