Shemeska
Adventurer
I'd cover the city in more than one book to be honest. I'd have a book covering the city, its history, the wards, have a chapter on specific portals and their keys, and short introductions to the major power players and groups in the city. Then I'd make a second book be something like a melding of Faces of Sigil and Factols Manifesto, devoted to detailing the current powers that be in the City of Doors in the current day - a couple of pages for each major personality, and a greater number with a page each. Then move on to describing the guild structure, the remaining factions or groups rising from the ashes of the Faction War, waxing groups like the Ring Givers who have legit claim to faction status, etc.
Also, for 3.5 material there's the basic overview of the city in the Planar Handbook, and the details from Expedition to the Demonweb Pits that Wolfgang Baur (who also wrote In the Cage: A Guide to Sigil) are also really very nice, and they add some cool locations.
I think I just barely scratched the surface with that. About a hundred pages, but my God there's so much more that could be done considering the amount of material there is to draw on and stuff to elaborate upon. I'd sell a kidney to see such a book written for 3e (though I might be on dialysis at that point, since I think I may have already pledged one for a FC:III).
Also, for 3.5 material there's the basic overview of the city in the Planar Handbook, and the details from Expedition to the Demonweb Pits that Wolfgang Baur (who also wrote In the Cage: A Guide to Sigil) are also really very nice, and they add some cool locations.
The Sage said:Initially, I would use the planewalker.com write-up for Sigil as a guide, and expand significantly on that -- drawing upon all the previous existing sources for the City of Doors, while including new portions of well-researched and detailed source material.
I think I just barely scratched the surface with that. About a hundred pages, but my God there's so much more that could be done considering the amount of material there is to draw on and stuff to elaborate upon. I'd sell a kidney to see such a book written for 3e (though I might be on dialysis at that point, since I think I may have already pledged one for a FC:III).