The World Serpent (Accoding to Volo)

[Vincent07]

From Volo's Guide to Cormyr:

The World Serpent Inn is a house fully as expensive as the Goose and with ready access to as wide a variety of goods and services.  It is said to exist in a demiplane of its own and to open via its many ever-shifting doors into a myriad of worlds.  What I saw on my visit leads me to believe this may well be true.

Elminster:  Of course it's true, ye dolt.  The doors are indeed portals that allow one to setp directly from the inn to or from various planes.  They allow dimensional travelers to avoid those violence-loving idiots of Sigil.  The World Serpent was crafted long ago by the archmage Alaurum of Toril, his friend Ilyndele of the Arcane, and the ilithid High One, Sharth.  Its usefulness as a little-known back door quickly convinced certain divine powers that it had best be controlled, so one of them who enjoyed constant congress with new and interesting beings took the name and appearance of Mitchifer and assumed control of the inn, decreeing it open to all.

By unspoken agreement, folk tend to set aside disagreements when they're in the Serpent.  The powers Mitchifer can hurl at them may have something to do with that.  He's not the only deity to be met in the common room of the Serpent, either.  Many powers come here to relax, so good behavior on the part of visitors is highly advisable.

..... ((skipping the part about how to get in))

Opening the door of the Serpent takes you into a dark, carpeted passage that seems full of eerie blue smoke or mist.  Along its walls are many large, identical wooden doors.  Those who look about keenly may notice that some doors appear or disappear or seem to drift along the walls from time to time in an endless, silent shuffle.

The passage opens into the common room of the Serpent, a large space whose distant walls are always lost in the mists.  Light comes from fluted pillars here and there and from a large shaft of ligh in what is probably the center of the room.  In the glow of that large shaft of light sits the ring-shaped bar.  It is in turn surrounded by tables of drinkers--all manner of beings, from grell to neogi to mind flayers to beholders and worse!

Within the bar stands Mitchifer, master of the Serpent, who greets all visitors as if they're long-lost friends.  He's a fat man with rosy cheeks, a long white beard, and a great booming laugh.  I felt like laughing the moment he spoke to me, and I noticed that many beings he spoke with did just that.  He seems to have every sort of drink imaginable, and he whisks them to outlying tables by means of a small army of scurrying gnomes.

One of the efficient little servants takes you to a room if you express a desire to sleep at the Serpent.  Such escorts warn you, though, that all stays must be no more than a tenday since "space is so short."  Those who stay longer (I asked) find themselves left behind on a random plane--possibly without companions or belongings--as the Serpent melts away around them.

I recommend the Serpent for adventurers only.  Many guests have begun unintended quests and forays of incredible peril there.