The Catacombs form a broad, highly structured burial complex of circular halls, radiating chambers, side vaults, and repeated cells arranged around a central gathering space. Unlike a twisting natural cave, the geometry is deliberate and ceremonial, with concentric routes allowing characters to circle around threats, lose track of one another, or approach the same room from different directions.

That layout gives a GM excellent control over a large dungeon encounter. The central chamber can anchor a major confrontation, while the ring corridors create flanking paths and allow enemies to withdraw without simply running backward. Side crypts provide space for clues, remains, traps, or smaller fights, and the repeated architecture reinforces the oppressive scale of the burial site. In Tyrant's Grasp the catacombs fit the grim reaches around Gallowspire; elsewhere they can become a royal necropolis, city undercrypt, mass burial complex, or ancient ossuary built to hold far more dead than anyone expected to visit.