Sigil is a strange, Gothic, and often raucous metropolis that lies outside the rest of the Multiverse, inhabited by all manner of odd folk and ruled by the mysterious Lady of Pain and political parties—"philosophers with clubs", in more ways than one—called the Factions, all of them searching for the Truth behind the Multiverse. It is the hub of a vast network of magic portals that lead to every plane of the multiverse.
While the Lady of Pain is considered the ultimate ruler of the planar metropolis called Sigil, "the City of Doors", the Factions perform virtually all the actual administrative and practical functions of the city. They are the ones the people look to for authority; the Lady only gives edicts or appears personally under rare circumstances. Each of the Factions is based around one particular belief system; many of the Factions' beliefs make them enemies where their other goals and actions might have made them allies. All Factions hold many secrets from non-members and even their own members, for the fewer know a secret the more secret it is (and these are secrets of power, either wielded or potentially gained by the Faction's adversaries).
("Defiers", "The Lost"), who deny not only the gods' right to pass judgment over mortals, but their very divinity. They claim that the gods (whom they call "powers") are powerful but have limits and do not deserve worship. Instead, Athar priests channel divine power from what they call the "Great Unknown", or what they believe to be the true divine force behind everything. Their headquarters in Sigil is the
Shattered Temple, the former temple of the dead god Aoskar. The Athar are broadly derived from real-world atheists, agnostics, and Deists.
("Godsmen"), who believe that each life is a test, and that every person has the potential to become a god. Their headquarters is the
Great Foundry, symbolizing their belief that the multiverse constantly forges and refines all beings. Shares many parallels with Hindu and Buddhism. However, the ultimate goal is not Nirvana but apotheosis.
("Bleakers", "Madmen"), who deny that any belief system has any merit; as they see it, the universe has physical rules, but no metaphysical or philosophical ones, therefore any meaning in life must come from within. Their headquarters is the insane asylum of Sigil, called the
Gatehouse. They are derived from real-life existentialists and nihilists.
("Sinkers"), who believe in the sanctity and inevitability of entropy. They see the decay and destruction of the universe as necessary; for once it is destroyed all imperfections will be gone with it, paving the way for a perfect new world. Their headquarters is Sigil's
Armory, where they forge weapons as tools of destruction.
("The Dead") believe that both life and death are false states of existence, that there is a state of True Death which can only be accomplished by denying one's emotions and physical wants and needs (a conception similar to oblivion, but also conceivably to Nirvana). Their headquarters is the
Mortuary, where Sigil's dead are interred or cremated. Their philosophy is closely related to acosmism, with a more death geared ideal. The faction shares similarities with Buddhism and with the Stoics as well.
("Takers", "The Heartless") believe that those with power and ability have the right to own what they control and to take what they can from those who are unable to keep it, and that it is their right to exploit any situation to their advantage, regardless of how it affects anyone else. Their headquarters is the
Hall of Records, where they serve as the tax collectors of Sigil. They are derived from real-life Social Darwinists and the philosophies of Max Stirner.
("Guvners"), who believe that knowledge is power; they learn and exploit both the natural laws of the universe and the laws of society. Their headquarters is the
City Court, where they serve as judges and legal advocates. They recall the Sophists of Classical Athens.
("Indeps"), who reject the other factions and their bureaucratic, hierarchical dogmatism; in fact, they don't consider themselves a faction at all. For this reason, they don't have a factol or an official headquarters, though Sigil's
Great Bazaar serves as an unofficial one. They believe in individual freedom as the highest good and could be considered similar to libertarianism.
("Hardheads"), who believe that peace and stability can only be established under one rule — theirs. The planar faction known as the Harmonium is actually just a small part of a much larger political entity which rules over the entirety of the Prime Material world of Ortho. In Sigil, they serve as the city's police force, and their headquarters is the
City Barracks. They are related to present day authoritarianism, particularly religious evangelicalism and fundamentalism. It is strongly advised that visitors to Sigil never, under any circumstances, use the term 'Hardhead' in front of Harmonium members.
("The Red Death"), who believe in justice and retribution at the expense of all else. Their name does not come from "killing out of mercy," but rather "killing mercy." Their credo that mercy is for the weak, and the merciful should be punished. Appropriately, their headquarters is Sigil's
Prison, where they carry out the sentences of convicted criminals.
("Anarchists"), who believe that social order and man-made laws are inherently corrupt and must be destroyed—though none of their members can agree on what, if anything, should replace them. Like the Indeps, they don't have a factol or a headquarters, though they have many safe houses and secret meeting places.
("Signers"), who believe that everyone is the center of their own reality and that reality can be reshaped by the power of imagination. Their headquarters is the
Hall of Speakers, which houses Sigil's legislature. Some of them are solipsists, though most are not so extreme.
("Sensates"), who believe that accumulating experiential knowledge through the senses is the only way to achieve enlightenment. Their headquarters is the
Civic Festhall, which features an endless series of entertainments and a library of magically stored experiences. They are remniscent of ancient Epicurianism, as well as the more modern empiricism.
("Ciphers"), who believe that by tapping in to the 'cadence' of the planes and acting through pure instinct they can achieve a higher state of being. Their headquarters is the
Great Gymnasium, where members can train to improve their bodies and minds. Their philosophy could be considered similar to Taoism and Zen Buddhism.
("Chaosmen"), who believe that the only truth is revealed in chaos. The Xaositects have been quite accurately described as being "totally off their rockers, every one of 'em." Their headquarters is the
Hive, which is the most disorganized part of the Sigil ward of the same name. Some may consider their philosophy a slight twist to accidentalism, but a far more relevant parallel is the Cynics (Greek ??????? "dogs") of antiquity. There is even a gang of Xaositects called the "Starved Dogs Barking" featured in Planescape: Torment. Compare with real life
discordianism.
