Avalon () is an island featured in the Arthurian legend. It first appeared in Geoffrey of Monmouth's 1136 Historia Regum Britanniae as a place of magic where King Arthur's sword Excalibur was made and later where Arthur was taken to recover from being gravely wounded at the Battle of Camlann. Since then, the island has become a symbol of Arthurian mythology, similar to Arthur's castle of Camelot. Avalon was associated from an early date with mystical practices and magical figures such as King Arthur's sorceress sister Morgan, cast as the island's ruler by Geoffrey and many later authors.
https://en.wikipedia.org/wiki/Avalon