Neverwinter Campaign Setting, seriously you can read the press release over on Dorkland!
This and the Gates of Neverdeath, I have to say I got to wonder what going on over at Wizards.
There are dozens of example of city books, in fact I was involved with one a couple of years back. It based on the very city ever to be described in a book for a roleplaying game.
Let's look at the real first-ever RPG book focused solely on a city.
It no longer in print, but you get a PDF from RPGNow. Both the original and the Necromancer version.