Me and a few of my friends have lived in detroit our whole lives and we've spent our last two gaming sessions putting together our own little detroit in the dresdenverse. A few of the better locations and facts we've found are
~http://hubpages.com/hub/Detroits-Nain-Rouge the red gnome legend, throughout detroits history reports of a horrible red gnome appearing around all of the worst tragedies have been common. In our world we are making this creature a mysterious member of the winter court who wanders the streets of the city.
~A counter to the red gnome is the spirit of detroit.
http://members.fortunecity.com/fordkramermichigan/detroit/detroit.htm this statue supposedly watches over the city and embodies hope as it wards off the red gnome. We haven't incorporated it into our campaign yet but it's still an interesting fact.
~There are steam tunnels that run beneath much of the city, large dark tunnels that actually connect directly to a number of the buildings. An office I used to work in had a locked door at the bottom of some stairs that actually opened directly into the tunnels. In our city creation we decided it would be a wonderful place for a horde of ghouls to thrive, grabbing people from all over the city into their dark lair.
~At the corner of cass and bagley there is an old building that looks like it's barely standing which houses detroits very own underground goth scene known as City club, the place looks like its completely vacant unless you know where it is and the inside has a long bar, a couple dozen old couches, and a seperate room housing the dance floor. I don't think anything that went on there would surprise the patrons, people dressed as and acting as vampires is completely common, as is people with outrageous costumes of all different sorts. The large basement beneath the club is known as "the labryinth" and often houses insane concerts. In our campaign we have made this entire building a white court business but it would also make excellent accorded neutral ground as the bouncers at the entrance are always very careful about searching people for weapons and even the most bizarre creature wouldn't get a second glance here.
~Another thought we've had is that in the books it was mentioned that a number of ley lines pass through the great lakes. Detroit has a wheel design, with a number of "spokes" coming out from the center of the city. So our thought is that perhaps the reason for the design is that a number of powerful ley lines converge in the center of the city (which is known as campus marshus). This could also be part of the reason for both the decline of the city, being that any number of nasty creatures would want to control that flow of power and use it for all sorts of rituals, so detroit becomes a supernatural battleground and the mortals are just left to deal with the fallout.
One of our aspects of the city is UNORGANIZED CRIME, representing the fact that there is no "Marcone" or any ruling criminal body in the city. There are a seemingly unlimited number of criminals in the city but no structure, no one person to contact when you want to know whats going on in the streets. The average person is so desperate that crime begins to look like a viable option which leads to an extremely dangerous climate where you can never be safe.
Another one of our aspects which might provide some interesting insight to anyone thinking of doing a detroit campaign is A GLIMMER OF HOPE. For how dark and violent the city is, for all the poverty and all the abandoned bulidings that seem to make up the majority of the city there is a 2 or 3 mile square in the center that has started to rebuild and seems almost reminiscent of the well-off city detroit used to be. Starting right near greektown casino and extending over towards comerica park there are a number of nice restaurants, a couple of churches, a theatre (plays not movies). It's a place where you can walk alone in the middle of the night and not be afraid of being mugged.