its two soft door-posts of custard,
Its dais of curds and butter,
Beds of glorious lard,
Many shields of thin pressed cheese.
...It rose from its lake of mild in a mystic light of its own--in a greasy, buttery glow. It was the fairy aspect of Castle Chariot...
From T.H. White's The Once and Future King
Morgan LeFay is the lady of Avalon, thus placing her castle in Avalon. It has been interpreted as both a mystic island and the real world Glastonbury, but either way it is designated as Arthurs final resting place. Aside from Glastonbury, authors have moved her around from the Castle of Maidens in Edinburh to the Mediteranean possibly Sicily. But whereever she is geographically, her domain is always the Avalonian place of healing.