Tantlin

Carved from one of the largest icebergs in Stygia, Tantlin was the layer's largest city.

Geography
Mountains surrounding the city held major quarries that mined it for granite, basalt, marble, and chalk.

Trade
Close to the city were many icy portals that linked the Styx to the Prime Material Plane, making it a major cross-planar trading hub with traffic from non-devils that was second only to the layer of Dis. Though many only tolerated these non-devil visitors if their safe passage was guaranteed by a pit fiend or war devil.

Caravans from all across the lower planes were known to travel here.