Pandesmos

Pandesmos was the topmost layer of the plane of Pandemonium in the Great Wheel cosmology.

Description
Pandesmos was the most hospitable layer of the plane. The caverns were the largest here,  some literally thousands of miles across. Immigrants to Pandemonium tended to live on the surfaces of these massive caverns, which contained both cities and citadels, though these were very rare. Most caverns were abandoned to anything but wind. Most of the gods who claimed their realms in the Windswept Depths also made this layer their home. Despite the size of the caverns, they were as loud and windy as the rest of the greater plane. Entire nations could fill the cavern walls, but the strong winds prevented this from ever happening.

The Styx began here, fed by countless cold streams flowing along the walls of the otherwise rocky, subterranean wastes. Some of the streams even floated through the open space in the center of the caverns.

Dead-end tunnels with unusually strong winds (even for Pandemonium) often signaled that one was at a barrier and about to pass to the lower layer of Cocytus. Flat, square portals found in Pandesmos led to Limbo, the first layer of the Abyss and the Outlands. Yellow squares led to Limbo, red squares to the Abyss, and black to the Outlands. The portals were inconsistent, however, and sometimes sent travelers to the wrong planes.

Locations
One of the rare cities located here in Pandesmos was the Madhouse, a citadel controlled by a group of outsiders called the Bleak Cabal. The Madhouse was often used as a way point for travelers to Pandemonium. It was a sprawling city of poorly arranged buildings covering all of the walls of a large cavern. The citadel was divided into sections by multiple stone walls. Befitting its name, a high percentage of the residents of the Madhouse were deaf or insane or both.

Realms
Auril's palace of Winter's Hall was located here.