In Greek mythology, the Labyrinth (Greek labyrinthos) was an elaborate structure designed and built by the legendary artificer Daedalus for King Minos of Crete at Knossos. Its function was to hold the Minotaur, a creature that was half man and half bull and was eventually killed by the Athenian hero Theseus. Daedalus had made the Labyrinth so cunningly that he himself could barely escape it after he built it. Theseus was aided by Ariadne, who provided him with a fateful thread, literally the "clew", or "clue", to wind his way back again. The term labyrinth is often used interchangeably with maze, but modern scholars of the subject use a stricter definition. For them, a maze is a tour puzzle in the form of a complex branching passage with choices of path and direction; while a single-path (unicursal) labyrinth has only a single Eulerian path to the centre. A labyrinth has an unambiguous through-route to the centre and back and is not designed to be difficult to navigate.