...or an adventure that really delves into Sigil. I have a friend who's interested in taking his Clueless Primes to Sigil, but is kind of at a loss for what to do once he's there. I've recommended he run the first adventure in Well of the Worlds, but I'm personally a bit stumped, myself. So I'm asking you all: Are there any established PS modules or adventures that really get into Sigil, the Factions, and what makes the city so great? Definitely not Faction War -- that one is better run with at least a passing understanding of Sigil. I've been looking at some of the other modules but few stand out.
Eternal Boundary takes place in Sigil but isn't especially Sigilian. I haven't read Harbinger House in a long time but I recall it takes place mostly in Sigil. Most of the others take place more in the planes, it seems.
Looking through "A Guide to Sigil," I don't see much in the way of organized adventures, but there are maps and statistics for a number of enemies, odd portals and treasure caches in the Slags, a ruined part of the Hive left over from a Blood War battle that spilled in to Sigil. You don't get much more Sigilian than the Hive. Could make a nice dungeon-crawl sort of adventure for saying hello to Sigil. And hey, any Clueless that survive the job will have a notch on their belt! :^)