Tír na n-Óg

Tir na n-Óg was a planet on the edge of Mutter's Spiral.

History
Tír na n-Óg was created by Goibhnie, who wanted to see the sociological effects of making a world. On the world there were creatures like those of the myths of Earth, such as the unicorns, there known as Ceffyl.

There was a link between Tír na n-Óg and Earth due to a stone circle on Earth being a gateway. This allowed many humans to go to Tír na n-Óg by accident. At one point the Seventh Doctor and Ace went there by accident and restored the sun, there known to locals as Arawn's Wheel. Once the Doctor had saved it, he closed off the portal and gave Arawn's Wheel 2,000 more years. (PROSE: Cat's Cradle: Witch Mark)

Prester John heard that you should never drink or eat when you find yourself in Tir na n-Óg, or else you would become bound to that world. (PROSE: Warring States)

Behind the scenes

 * According to Irish mythology, Tír na nÓg is the Land of Eternal Youth where no man ages.