Shadow Spire

The Shadow Spire was the home and prison of Auteur, a former Godparent of Faction Paradox whom the rest of the Faction disowned and locked away. It consisted of a crumbling black lighthouse located on a rocky shore within "a forgotten day", its surface only covering "a few miles of stolen concept". Its skies were red, like those of the Eleven-Day Empire. (PROSE: Going Once, Going Twice)

History
After Lolita destroyed the Eleven-Day Empire, (AUDIO: The Shadow Play) a "small cabal" of surviving members of Faction Paradox found refuge in Auteur's pocket dimension, living in the Spire. These included Mother and Father, a few dozen Cousins and a handful of Siblings, including the Brothers Intrepid and Gustav. (PROSE: Going Once, Going Twice)

Behind the scenes
To go hand-in-hand with Auteur being implied on numerous occasions to be Astrolabus's future self, the Shadow Spire and its surrounding dimension evoke the imagery of Astrolabus' TARDIS as it appeared in its first appearance in COMIC: Voyager. However, it is worth noting that at the end of that story, the lighthouse-TARDIS departed from the "rocky shore" of the dream realm, long before the point in his timeline at which Astrolabus could plausibly turn into Auteur.