A vertical district carved in a semicircular ring around the southern portion of the city. Ringhollow occupies a valley-like series of deep shafts and excavated chambers that descend well below the surface. The Woven who live here prefer the enclosed spaces, and several Carceri structures form the load-bearing walls of the deepest chambers in ways that make the distinction between district engineering and biology difficult to maintain.
Factories, forges, and alchemical laboratories operate in Ringhollow, taking advantage of heat produced by veins and nodule-like clusters of thermic fungus that thread through this particular region of the city's underground. The fungus also drives a crude geothermal power system: heat exchangers tapped into the largest nodules feed steam turbines that supply the district's factories and, increasingly, the Wire repeaters and electrical systems of adjacent neighborhoods. Ringhollow's power output is the closest thing Nod has to a municipal grid, though the engineers who maintain it would object to calling it a grid, on the grounds that a grid implies someone planned it. The privacy of depth attracts communities that prefer it, and the air in the lower levels is close enough that most surface-dwellers find it uncomfortable after an hour but the Woven do not seem to mind.