Arianrhod, which translates from Welsh as "Silver Wheel", is the Celtic goddess of the Moon, Time and the Sea.   Mistress of Caer Sidi, the Tower of Initiations, she watched over the dead between their incarnations and guided them into the next life.
Caer Sidi was also the Tower where Bards and poets
learned wisdom of the stars. Many ancient astrologers took their observations from the positions of the Moon and its progress in relations to the stars - 'Caer Arianrhod' - Arianrhod's Castle.
In Wales, the name for the Corolla Borealis is
'Caer Arianrhod' and as a meditative tool or glyph,
it provides a glimpse of both the past and the future;
however, one must follow the path with an open heart and mind.

As a pathworking, the Spirit of Arianrhod is an eternal quest or thread that has no beginning or end.
She is a symbol of prophecy and dreams.

In myth, Arianrhod was the daughter of Don, sister of Gwydion, and niece to Math, son of Mathonwy.
When Math looses his foot-holder, Arianrhod is suggested as a replacement. One of Math's conditions to hold the position was that she be a virgin.  The test for this involved a magical test - stepping over Math's wand.  The moment that her first foot crosses over the wand, one boy is born - Dylan.  As the second foot crosses, a second son is born - Llew.  Llew is grabbed and taken away by Gwydion to raise as his protégé.   However, shamed as she was in front of the court of Math,
Arianrhod places a series of geise (curse or taboo) on Llew:
1. That he shall have no name unless she gives it
2. That he shall have no arms unless given by her
3. That he shall have no human wife unless given by her.

Gwydion was outraged by these curses and worked to break them.  He disguised himself and the boy child as shoemakers and traveled to Caer Arianrhod.  When Arianrhod went to have shoes fitted, the boy child threw a stone at a bird and deftly hit it.  Arianrhod commented on the child's skillful hand.   At that Gwydion revealed himself and the child and stated that she had just named him -  Llew Llaw Gyffes, the Shining Skillful Hand.
This threw Arianrhod into a firey rage and
she stormed back to Caer Arianrhod swearing that
the boy would never bear arms or have a human wife.

Again Gwydion tricked Arianrhod into breaking her own curse.  He disguised himself and Llew as travelers and sought refuge in Caer Arianrhod.
While they were there Gwydion caused an illusion showing a powerful armada of ships advancing on Caer Arianrhod.  Making ready for battle Arianrhod threw open her armory and armed her retainers.  Gwydion suggested to Arianrhod that she give arms to him and Llew (still in disguise) and they would fight at the defense of the castle.  She readily agreed and thereby, unwittingly, granted arms to her son,  breaking the second curse. Gwydion then revealed themselves to Arianrhod and told her that she may as well take the arms
back from her son, as there really was no battle to be fought.

Enraged at being tricked a second time, Arianrhod took comfort in her third curse - that Llew would have no human wife.  Gwydion, upset at the cruelty Arianrhod was showing her son, vowed to break this curse also.   Gwydion went to King Math and explained Llew's plight.  Combining their magic they created a woman made of flowers, Blodeuwedd, to be wife to Llew, and broke Arianrhod's third curse.

Humiliated by King Math, thwarted by her son, forsaken by her brother, Arianrhod retreated to her castle Caer Arianrhod.   Here she later drowned when the sea reclaimed the land.

Silver Circle of Ancient Power,
Join me in my sacred space
Lend your strength,
Weave the spell,
Your essence i embrace.
Primal Goddess of Feminine Power
Come join me in my rite
As I celebrate the full moon
The symbol of your might!
(Ramoth 5/25/2002)

These above landed in my mailbox and I loved them! Used with permission, written by  Ramoth13@webtv.net 

Mistress of the otherworld tower of initiation. Caer Sidi, where poets learn starry wisdom and where the dead go between incarnations

Caer Arianrhod is the circumpolar stars, to which souls withdraw between incarnations; she is thus a Goddess of reincarnation.

Among the Celts of Wales, She was a Goddess of Childbirth, the Moon, Fertility and Fate. She derives Her name from the Milky Way and/or the zodiac and the Moon.

Her Signs and Symbols

The Corona Borealis (Northern Starcrown) is named Caer Arianrhod in Welsh - the self-same constellation which is associated with Ariadne, a Greek resonance of Arianrhod. It was thought as the palace of Arianhrod, while she herself was the moon.

She is often represented by silver, wheels, and a sheaf of wheat.