Sigil: the City of Doors. It’s considered by some to be the jewel of the Outlands, the nexus of power of the multiverse, a place of great beauty or ugliness. Every day in Sigil, deals are made that seal the fate of hundreds and thousands, negotiators barter for peace in the Blood War, and factotums seek the truth to the meaning of everything. People die, ideals are born, and great power is wielded with the flick of a finger. Sigil is a place of contradictions. It’s the center of an infinite multiverse. It’s an embattled neutral ground in a battlefield of philosophy. It’s the City of Doors and yet it’s called the Cage. It’s home to pit fiends and solars, devas and yugoloths, all living and drinking and socializing in more or less peaceful state. 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".