Vigil's Sewers form a branching network of stone channels carrying dark water beneath the city, crossed by improvised plank bridges and interrupted by collapsed walls, raw cave breaches, rubble, bones, and small storage or hideout spaces. The system feels maintained in places and broken in others, giving it more character than a uniform grid of identical tunnels.

For a GM, the narrow walkways and bridges are the defining tactical features. Control of a crossing can control an entire branch of the sewer, while the water channels make forced movement dangerous and slow pursuit. Cave breaches provide alternate entrances for creatures or fugitives, and the small dry rooms are natural places for caches, evidence, or ambushes. In Tyrant's Grasp: Last Watch, the sewers give access beneath Vigil during a period of crisis. Elsewhere they can serve as city sewers, smuggler routes, plague tunnels, thieves' passages, or any urban underworld where the safest ground is also the most predictable path.