The Underworld is divided along political lines into Domains, which are similar to nations or kingdoms of the surface. Each Domain is a sovereign state, under the control of its Lord (the actual title varies from Domain to Domain, but the general descriptive term is “Lord”).
Some Domains are open to all – these are referred to as Freeholds, and are centers of commerce and culture for the Underworld, attracting Traders selling their wares, as well as other Guild members looking for employment. They make excellent locations from which to begin adventures, or to use as home bases for characters.
Other Domains have restricted access. These Domains, known as Fastnesses, do not open their gates to strangers. Their Lords stay within their walls (if they have walls), and none of the population (if there is any) ventures outward, except in the rarest of circumstances. These are places of mystery for most characters, who will have never been inside such locations before (assuming, naturally, that they manage to get inside this time, which is doubtful). Many Fastness Domains are very aggressive about defending their borders from perceived incursions, making these types of locations very dangerous.
There are many Domains in the Underworld, ranging in size from single chambers to huge territories covering many square blocks of area, as well as multiple levels. To try to map them would be folly – instead, directions are given in relation to the nearest corresponding point on the map of the New York City subway system. Domains also vary in their RadCount, the amount of ambient Radiance energy in the Domain. The higher the RadCount, the more bizarre, strange, and mysterious the Domain is likely to be.
What follows are several of the more well-known Domains of the Underworld, to use both as examples, and as common elements that can be featured in any campaign. Each entry gives a brief description of the Domain, including its subway-map landmark, local RadCount, and information about its Lord.