The Outer wall is a barrier against the dangers from outside the city. In its shadows is another barrier, one from hope, comfort, and warmth.
Sky street (and the blocks around it) are odd. The shadows are darker. The air is damper. The mood is bleak and errie. The street is silent, all the noise muted somehow. However, you can always seem to hear someone crying.
Everyone has to live and work somewhere.
The street is wide, and smoothly paved, with trees planted along the sides. The houses are mansions and palaces, each surrounded by stone and ironwork walls that are as much decorative as they are protective. These are the summer homes of the Princesses, and ladies of privelage.
All spell casters gain their abilities through a form of demon possession. So in order to gain magical abilites, PCs must track down and trap demons. Of course there are some pretty powerful demons, if the demon is stronger than the PC, the PC could find themselves subjugated to the Demon's will.