Many writers tell that after his last battle at Camlann, the wounded King Arthur was laid in a barge and sailed to the Isle of Avalon (Avalonia translatesas Apples) for his wounds to heal. The Isle of Avalon is described with a fair amount of detail, however its exact location is usually left vague. Some writers state that Arthur is still alive on the Isle of Avalon and will return to Britain to be their future king in the country's hour of need.
Some texts do attempt to locate the Isle of Avalon. The Isle of Man has been presented being the Isle of Avalon, as well as Bardsey Island in northern Wales. There is a less well-known story, The Death of King Arthur, that may have been intended as an addition to Geoffrey of Monmouth's History. Richard Barber's Arthurian Legends, whose manuscripts date from the fourteenth century, claims that the king gave orders that he should be carried to Gwynnedd, for he intended to stay in the Isle of Avalon, a pleasant and delightful placewhere the pain of his wounds would be eased.
Geoffrey of Monmouth tells that King Arthur was mortally wounded and was carried
off to the Isle of Avalon, so that his
wounds might be attended to. He handed the crown of Britain over to his cousin Constantine, the son of Cador Duke of Cornwall. On the Isle of Avalon, Arthur is looked after by Morgan
Glastonbury has been claimed as the Isle of Avalon. At that time Glastonbury Tor would have been an island in the fenland here. Glastonbury claims to be the Isle of Avalon, the site of King Arthur's, and the site to which the Holy Grail was borne to by Joseph of Arimethea. The claim appears to date back to some monks in the late twelfth century, who decided to cash in on the popular Arthurian legends circulating at that time. They claimed to have found the tomb of Arthur in 1190, with an inscription conveniently claiming Glastonbury to be Avalon. This find brought many pilgrims, and hence money, to Glastonbury.
So was the Isle of Avalon a real place - there is no real evidence to tie it to one.
King Arthur introduction