Sigil is located atop the Spire in the Outlands. It has the shape of a torus; the city itself is located on the inner surface of the ring. There is no sky, simply an all-pervasive light that waxes and wanes to create day and night. Sigil cannot be entered or exited save via portals; although this makes it quite safe from any would-be invader, it also makes it a prison of sorts for those not possessing a portal key. Thus, sometimes Sigil is called "The Cage". Though Sigil is pseudo-geographically located "at the center of the planes" (where it is positioned atop the infinitely tall Spire), scholars argue that this is impossible since the planes are infinite in all dimensions, and therefore there can never truly be a center to any of them, let alone all of them; thus, Sigil is of no special importance. Curiously, from the Outlands one can see Sigil atop the supposedly infinite Spire.
Sigil contains innumerable portals that can lead to anywhere in the Dungeons & Dragons cosmology: any bounded opening (a doorway, an arch, a barrel hoop, a picture frame) could possibly be a portal to another plane, or to another point in Sigil itself. Thus, the city is a paradox: it touches all planes at once, yet ultimately belongs to none; from these characteristics it draws its other name: "The City of Doors".
The ruler of Sigil is the mysterious Lady of Pain. The Lady is sometimes seen in Sigil as a floating, robed Lady with a face bearing a mantle of blades. The Lady does not concern herself with the laws of the city; she typically only interferes when something threatens the stability of Sigil itself. However, she is an entity of inscrutable motives, and often those who cross her path, even accidentally, are flayed to death or teleported to her hidden Mazes, lost forever. It is widely believed that she never speaks, although some unconfirmed (and, most would argue, highly questionable) rumours to the contrary do exist. Sigil is also highly morphic, allowing its leader to alter the city at her whim.
Sigil is, theoretically, a completely neutral ground: no wars are waged there and no armies pass through. Furthermore, no powers (such as deities) can enter into Sigil; the Lady has barred them from the Cage, though some disguised avatars have made it in and been promptly dispatched by the lady. It is also of great interest to them, as they could use Sigil to send their worshippers anywhere, and it is at the center of the Outer Planes. Of course, Sigil is hardly peaceful; with such a condensed population, consisting of everything from angelic devas to demonic glabrezu, violence is common, usually befalling the foolhardy, the incautious, or the poor. Most natives of Sigil ("Cagers") are quite jaded as a result of living there.
People coming to Sigil from the Prime Material Plane are often treated as clueless inferiors by the planar elitists who dwell there. They are thus widely referred to as the "Clueless", or more charitably, as "Primes".
Sigil is divided into six districts, called wards:
* The Hive Ward, the slum and the ghetto, home to the poor, the rogues, and the unwanted dregs of the city.
* The Lower Ward, an industrial district, clogged up with the smoke from the foundries and from the portals to the Lower Planes.
* The Clerk's Ward, an affluent district, home to most of the city's lower-rung bureaucrats and middlemen.
* The Market and Guildhall Wards are the home to the traders, craftsmen, artisans, guild members and other members of the middle class.
* The Lady's Ward, the richest and most exclusive section of the city, is home to the elites of society and of its government.
(the above information from Wikipedia)
Factions and Organizations
Factions as described in the original boxed setting. The Faction Wars never happened.
If the organization has a base of operations, it is listed in parentheses.
The Steeple - (Lady's) An association of Celestials dedicating to helping the impoverished and downtrodden. The Playground - (Lower) A business run by Devils, known for its hedonistic tendencies. The Underworld - (Unknown) Sigil's most successful crime "family." All of its known important members are intelligent undead. Universal Education Center (Clerks) - Sparsely populated building dedicated to helping all intelligent beings better themselves--mostly they distribute pamphlets. Celestial Bureaucracy, Sigillian Office - (Clerks) the local connection for the "Chinese" mythology. Planewalker's Guild - (Market) Headquarters is on the Infinite Staircase, but they have a thriving hall in Sigil. Winter Circus - Performance artists a la the Cacophony Society. The Orpheum - (Guildhall) Sigil's bardic university, containing 12 separate colleges. Venturans - (Hive) Combatants who have survived at least 5 fights at Venture's (gladiatorial fighting arena). A brotherhood of killers. Thrice-Damned - (Lower) A small association of beings who provide paralegal substances such as addictive drugs and poisons. Brotherhood of the Notched Blade - (Lower) Veteran soldiers who gather at the Notched Blade private club in the Lower Ward. Path of Enlightenment - (Lady's) A multidenominational monastery and retreat. Gardener's Rest - (Market) An Inn catering to nature-lovers.
Most deities have some followers in Sigil, and there are over a thousand temples and shrines.
Basic Premise: The Keeper's Finders: the PCs are an elite extraplanar mercenary team that gets sent out on missions by a near-epic mage who looks like a blue Pit Fiend (or is it an advanced Pit Fiend with near-epic casting ability?). The Keeper, as this true neutral outsider is known, has his fingers in many pies and hires out merc teams to deal with problems for clients of all shapes, sizes, and alignments. The heroes will have a homebase of sorts in Sigil, but adventurers can literally lead to anywhere in the 'verse. I am using the original factions (pre-faction war). Applicants should take some time getting familiar with link Planewalker dot com.