The Ark continues to rebuild itself after the destruction wrought by the battle that ended the Human-Covenant War. Like icebergs, the Forerunner constructions on the surface are only a tiny part of the whole.
Partial-printing creates a terraced landscape of plateaus supported by colossal columns and the substructure of the Ark dominates the space with gigantic vertigo-inducing cavities that allow views deep into the superstructure beneath. The surface demonstrates the building techniques and foundations of a Refugia still being terraformed, with the layered strata giving a tantalizing hint of the Forerunners' unfinished design.
Even incomplete, the exposed vein-like layers have a raw beauty of their own and complement the sleek and sculptured metallic lines of finished Forerunner architecture nearby. Mineral deposits with exotic material properties scatter the surface, and new paths are created by massive shifting plates, their purpose known only to the long dead race that created them.