The Fortress of Sorrow is a brutal jungle stronghold built amid swamp, heat and visibly unnatural construction. Wooden palisades and clay-reinforced walls enclose a complex partly supported by the enormous ribcage of a long-dead creature, giving the fort an unmistakable skeletal silhouette. Pools and streams of molten rock cut through sections of the site, and a massive dragon skull pours lava from its open jaws as one of the fortress's central landmarks.

The expanded map set gives a GM several encounter zones rather than one courtyard. Palisades and gates create defensive choke points, the rib structure breaks up open interiors and lava makes direct routes dangerous or impossible. Exterior swamp and jungle provide a very different approach from the fiery ground within the walls, allowing an assault to escalate as characters breach deeper into the fortress. In Age of Ashes: Cult of Cinders, the location is a major Mwangi stronghold; outside the Adventure Path, it works as a volcanic war camp, cult fortress or monstrous citadel whose architecture looks assembled from the landscape's most violent materials.