Sigil is the bustling crossroads of of the multiverse, full of portals leading to every known corner of existance.
You look lost, sirrah. Walk with me through the murky twilight for a moment and I’ll teach you the dark of things—that’d be the secrets, for a clueless traveller like yourself. Mind you don’t brush against the grime; there’s lots of soot-stained walls here. Now, sir prime, look up. Makes you dizzy, don’t it, seeing the city of Sigil above you? See, living in an impossible city ain’t always simple. You need a guide. That’ll be twelve silvers.
Oh, those fellows? Dabus. They speak to each other with those illusions. They’re servants of the Lady of Pain, who rules the City of Doors and keeps it safe—No, I don’t mind questions.—It’s called the City of Doors ‘cause it’s the center of the multiverse, or leastways, a body can get anywhere from here through the city’s portals. It’s also called the Cage. Why?
Sigil’s a cage for everyone: for the celestials, for the fiends, for the tieflings and the Clueless, and for the Lady. That’s why the cutters who set their cases—uh, their homes—in Sigil call themselves Cagers. The Cagers who know the place best are us who teach: we’re known as touts. My name’s Etain the Quick, and I do my level best to tell a cutter everything he needs to know to survive in Sigil. Not everything there is to know, mind you: That’d cost extra.
Sigil’s the Crossroads, the great shudderin’ home to all the planewalkers of the multiverse. Under the Lady’s watchful and serene gaze, Sigil stays out of the politics and bloodshed of the conflicts raging throughout the planes, especially the Blood War. No matter what a cutter hears, most of the planes ain’t that friendly to strangers, whether they’re planar or prime or something else. Whether they’re living in wealth or squalor, smart cutters set up their cases in Sigil.
The Lady creates portals that lead everywhere, and when she wills she closes them. Most of the simple portals look like doorways; they only take cutters elsewhere when they carry the right key, and a key could be anything—a silver blade, a secret word, or an elaborately illuminated deck of cards. Because the city’s doors lead everywhere, everyone comes to Sigil sooner or later, even if they’re just passing through. That’s when a sharp tout latches onto them, whirls them through the sewers and the jink-shops, and takes his fee. Sure, it’s not polite, but every-one’s a cynic in Sigil, and the Clueless pay the price for their ignorance. Oh, no, I’m not calling you ignorant, sir prime! You, I respect!
—Etain the Quick, Tout