Clearly rooted into the celtic and english folklore about Avalon, but I am not so knowledgeable in the matter to give a specific explanation for the lyrics.
From what I found out googling here and there, Annywn is the term for the otherworld, and the goddess referred in the lyrics may be Brigid, since there are 19 virgins, labeled "Daughters of the flame", tending to the monument made in her honour.
Clearly rooted into the celtic and english folklore about Avalon, but I am not so knowledgeable in the matter to give a specific explanation for the lyrics.
From what I found out googling here and there, Annywn is the term for the otherworld, and the goddess referred in the lyrics may be Brigid, since there are 19 virgins, labeled "Daughters of the flame", tending to the monument made in her honour.