This will end up being the home for all of the information that we can find on the Lower Ward seeing as that appears to be our initial launch point, and I've been tasked to research it. That said, if anyone else has information that they think is relevant or useful, please post it here.
It's late at night for me, so I`ll add more to this in the coming days, but here are a few links to get us started.
Locations in Sigil (includes the Lower Ward): http://www.deathstar.org/~krlipka/ps/places/sigil/tsr-sigil.html
Maps of Sigil: http://www.shadowland.org/Planescape/maps.html
The Lady's Ward/The Lower Ward: http://www.shadowland.org/Planescape/images/lady2.jpg
The Lower Ward: http://www.shadowland.org/Planescape/images/lower.jpg