The Infinite Staircase is what it sounds like: a set of stairs that stretches beyond all horizons, takin’ a cutter to the depths o’ the Hells or to the heights o’ the Heavens. ’Tis a spiralin’ silver staircase with ivy hangin’ from it here an’ there. No support can be seen for the Staircase, which is twenty feet wide, and is inside a silver tower shaft. Along the Staircase are platforms o’ wood or marble, some straight, some curvin’, and each one leadin’ to doors or even more stairways. The platforms are of many makes, from small doorsteps with a wooden door to large platforms thatstretch out o’ sight wit’ yawnin’ archways.

Openin’ one o’ these doors, it opens into a quiet, out-o’-the-way area somewhere on the planes, coming out a door that the locals pay no mind. It could be in an abandoned building, or in the corner of a dusty basement, though usually the door takes a planewalker to an inhabited burg o’ some sort. So, what kinds of planes are these? Any kind. The Staircase connects to any place in the multiverse where creativity and imagination springs up. ’Tain’t as pleasant as it first sounds, rube. This could mean a trip to a pain garden in Baator or a potter’s shed on the Prime. Bloods can usually get a feel for the type of place a door goes to by the surroundin’s and the materials ’tis made of. I once stumbled across a door of stretched, humanoid skin painted with bloody symbols, on a shadowy landing wit’ the soft sound o’ moans comin’ from somewhere just beyond knowin’. I was sure that weren’t what I was lookin’ for.

Hoofed it up another staircase right quick. Most doors ain’t so obvious, but there’s always some clue. Climbers of the Infinite Staircase may have a trip ahead o’ them. No graybeard knows how many doors there be, though many have tried to find out. If they have a specific door they’re heading for, it may be days away. That’s a lot of walking up or down, and the Staircase ain’t kind to berks who cheat with magic. Fliers who stay close to the stairs do all right, but if they
try to take a shortcut to another set o’ stairs or landing, they’re likely to get sucked into a fold in space and spit out onto the planes somewhere. Teleporters risk the same danger, as does
anyone who jumps, dives, or is pushed off the stairs.

Those walking the Staircase may meet the occasional fellow traveler or see no one for days. The Planewalker’s Guild has taken over a massive landing as their kip high up on the Staircase, and I can tell ye that a body can do worse than joinin’ up with those bloods. A fine bunch, interested in nothin’ so much as learnin’ the paths o’ the planes. Travelers might also run into the lillends, servants o’ Selûne, the moon goddess. The Staircase starts in the goddess’s palace, and she takes an interest in who’s usin’ it. If’n the planewalkers have a close relationship to creativity, chaos, and good, they may get help from the lillends, mostly by getting directions or warnings o’ dangers. If the lillends feel the planewalkers themselves are one o’ those dangers, they won’t be shy about nickin’ the “intruders”.

The Staircase is one o’ the most useful of all planar pathways, but planar travelers often choose other routes. I’ve always found it a great way to get about, like the City o’ Doors with all the different kinds o’ portals, but for many berks, ’tis real lonely. It can be mighty tiring to travel the Staircase, and caravans are right out. The other planar pathways don’t provide as many destinations, but the ones they do are mapped out much better. But the truly adventurous, or the just plain lost, can be found walkin’ up and down the silver steps, openin’ doors that lead to worlds beyond the ones they know.

-Hajzeek Gnarl-Hoof, Bariaur Planewalker
From the Planescape Campaign Setting on Planewalker