Sungrave Tunnels

The Sungrave Tunnels first appear in Iron Gold as an ancient, labyrinthine network beneath the Martian city of Sungrave. Their howling winds, ice-slicked passages, and hidden peepholes offer clandestine vantage points over the stratified activities of the city’s castes. Across the series the tunnels evolve from a mere atmospheric backdrop into a strategic under-city artery that characters exploit for covert movement, surveillance, and eventual confrontation.