The stone is still there. It's about the size of a Mini and is perched on top of smaller stones. Like Stonehenge it was probably constructed by the Drewids. However, it is called King Arthur's stone for the following reason. Whilst King Arthur was walking along Cefn Bryn (back bone) he stopped to remove a stone from his shoe which he then cast aside, when the stone landed it grew to the size it is today.