- You may be looking for the alternate dimension with the same name.
Avalon, a planet with six moons, was discovered near the end of the Earth Empire. Once home to an advanced race, it was colonised by humans, who set up a nation named Elbyon, which was able to use what was believed to be magic by accessing the planet's old network of nanomachines, which allowed those with the right level of skill to manipulate the world around them. The First Doctor visited Avalon circa 3025, where his actions resulted in the destruction of the nanite network to stop a powerful 'sorcerer'. (PROSE: The Sorcerer's Apprentice)