Craig Gwrtheyrn (Vortigern’s Rock).
Craig Gwrtheyrn is in the neighbourhood of Pencader in Carmarthenshire. According to an old legend, the disreputable old British King Vortigern, built a castle here in the fifth century; but he and his castle were destroyed by fire from heaven. There is also a story that Owen Glyndwr sleeps in a cave here.
From ‘Folklore of West and Mid-Wales’ by J C Davies (1911).