Tantlin

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

Description
Every structure and road in Tantlin was carved either directly from the iceberg or from ice molds. It's arranged in concentric circles, with the inner areas reserved for the most powerful devils and the extra-planar visitors confined to the outermost ring.

Geography
Mountains surrounding the city held major quarries that were mined 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. However, 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. Even mummies and liches have been known to travel from Ankhwugaht to engage in commerce. Though the biggest industry for devils in Tantlin is doing paperwork for all of the Nine Hells, making copies of various magic scrolls, books, and contracts.