Saint Collen, Tollen
Collen once lived in a hermitage on the slopes of Glastonbury Tor. One day he heard two men speaking of Gwynn ap Nudd, and he reproached them for speaking of pagan beliefs. They replied that he had offended Gwynn ap Nudd and would have to suffer the consequences.
The following day a messenger arrived from Gwynn ap Nudd and invited Collen to visit the King, but Collen refused. The messenger arrived again the following day, this time making thinly disguised threats. For several more days the messenger arrived, each day increasing the severity of the threats.
Finally, Collen consented to visit Gwynn ap Nudd and, armed with holy water, climbed Glastonbury Tor, where he entered a magical castle on its summit. Gwynn ap Nudd offered him food, but Collen refused, knowing that if he ate he would be condemned to spend the rest of his days in the Otherworld. Collen sprinkled holy water all around him and in an instant the castle and all its inhabitants vanished, leaving Collen quite alone on the summit of the hill. From that day to this the fairy castle of Gwynn ap Nudd has never been seen again.
This story, although based on a seventh- or eighth-century tradition, was not written down until the sixteenth century, and it appears to have been much altered over the years.