Avalon (The Shadows of Avalon)

 is an alternate dimension created by Gallifreyan Interventionists. It exists in the unconscious mind of King Constantine, whose dreaming gives it substance. It was made for the Catuvelauni, a Celtic tribe, to escape Roman invaders. Also living in Avalon are the Fair Folk, Silurians who were unintentionally brought along with the Catuveluani. The TARDIS hits a weak spot in 2012 between Avalon and England, causing its apparent destruction. The collision opened a rift between the dimensions. Before the rift was sealed, Avalon was where Compassion completed her transformation into a TARDIS. (PROSE: The Shadows of Avalon)