Avalon (probably from the Welsh word afal, meaning apple) is a legendary island featured in the Arthurian legend. It first appears in Geoffrey of Monmouth's 1136 pseudohistorical account Historia Regum Britanniae ("The History of the Kings of Britain") as the place where King Arthur's sword Excalibur (Caliburnus) was forged and later where Arthur was taken to recover from his wounds after the Battle of Camlann. Avalon was associated from an early date with mystical practices and people such as Morgan le Fay.
Read more about Avalon: Etymology, Connection To Glastonbury, Non-Arthurian Notability