The Arcanium was the personal refuge of the Ultramarines' Primarch, Roboute Guilliman, within the Fortress of Hera on Macragge. As a boy, Guilliman would seek solitude in a remote spot of the Crown Mountains, to read, write, and reflect.[1] Later, as Consul of Macragge, he built a small structure there with his own hands, preserving the spot as his private sanctum.[2]
It was in the Arcanium that Guilliman composed the Codex Astartes.[2] As of M41, the Arcanium had been absorbed into the fortress's Library of Ptolemy, where Guilliman's manuscript of the Codex still resided, inscribed into four enormous volumes, each one metre long and one-third of a metre thick.[1] Its significance to the Primarch was a closely guarded secret, since, as Chief Librarian Tigurius confided, he intended to preserve the peace of the refuge that Guilliman had first sought there, rather than turn it into a trampling ground for pilgrims like the Shrine of Guilliman.[1]
Sources
- 1: Courage and Honour (Novel), Chapter Three, pgs. 51-54
- 2: Rules of Engagement (Short Story)
