I think Doc's idea was having not a single marketplace, but a number of small markets scattered through the city -almost one per ward. These small markets would have different type / quality items depending on the ward where they are. The number and variety of available items in the market district would be notoriously bigger than in other wards -hence the name.
By the way, I'm making slow progress lately. I left ward drawing definition aside to test some graphical stuff -colors, textures, and such. Here's how I think Wards Plan would look:

I'm still in trouble with temple district -I don't know "what" to draw, since there's no defined position regarding crossgate religion. I sketched temple district a bit, so I'm leaving it until some interesting stuff about whoremaster religions pops up (down to the bottom of the "to do" list). Yes, it looks like I have a "to do" list now, but I don't know how it started...