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.
A plague has hit the local area.
In humans it affects only the most vulnerable, the children and the very old, and even than it's little more than a summer cold. 24 hours of sniffles and then it's gone, barely noticeable really.
To sheep however it is fatal and the whole economy of the area is in serious trouble. If this keeps up the area could well be facing famine.
Somebody (enter the PCs) must find the rare herbs needed to make a cure.