Cathedral Ruins open a once-sacred complex to the sky. Broken stone, ash-dark flooring, a fallen bell, damaged walls, scattered debris, and surviving sacred architecture mark the ruined nave, while lower rooms and attached spaces extend the site beyond the obvious central hall. A palisade and exterior ground give the ruin a defensible boundary even though the building itself has lost much of its protection.

For a GM, the cathedral offers several encounter scales in one location. The open nave supports a large confrontation around the fallen bell and rubble, while the lower vaults create tighter spaces for investigation or a second phase of combat. Broken walls allow unusual approaches, and the surviving religious features can become objectives or landmarks without additional dressing. In Tyrant's Grasp it fits the battered fortifications and sacred sites of Last Watch; elsewhere it can be a war-damaged temple, abandoned monastery church, undead-haunted cathedral, or ruined sanctuary pressed back into service as a strongpoint.