The Tor has been associated with the name Avalon, and identified, since the alleged discovery of King Arthur and Queen Guinevere's neatly labelled coffins in 1191, with the legendary hero King Arthur. Modern archaeology has revealed a fort, dated to the 5th century.
With the 19th-century resurgence of interest in Celtic mythology, the Tor became associated with Gwyn ap Nudd, who was first Lord of the Underworld, and later King of the Fairies. The Tor came to be represented as an entrance to Annwn or Avalon, the land of the fairies .
Christopher Hodapp asserts in his book The Templar Code For Dummies that Glastonbury Tor is one of the possible locations of the Holy Grail. This is because it is the location of the monastery that housed the Nanteos Cup.
Another speculation is that the Tor was reshaped into a spiral maze for use in religious ritual, incorporating the myth that the Tor was the location of the underworld king's spiral castle.