The skull is your center of power, the ribs are the highrises for the influential, and the center is the pit for the commoners.
If we assume that this creature's skeleton has some latent strength remaining, it might become an anchor for structures. Looking at the ribcage, you have hundreds of meters of flat space from head to tail, much of which is likely to be "protected" by ribs protruding upwards at various heights.
The skull, a cavity-filled but well-protected enclosure, would be the most fortified location. Along with its natural protection and space, it also has the spiritual benefit of being the head of the beast. This makes for a natural palace of sorts that is both practical and meaningful.
Stretching across the sand from skull to tail is a flatter, more open expanse lined by the ribs. This region is a likely space for commoners worshiping the monstrous skull or the rulers who take residence in it to erect initial shelters. Here you'd find markets and slums springing up, most likely with the well-off staying closest to the head and the poorest near the tail.
As the settlement grows, the ribs provide upward mobility. With some construction expertise platforms can be anchored into the ribs from the bottom up to the tips. These platforms become skyscrapers with as many floors as they can fit. Stairs, ramps, pulleys, or elevators could link them and they could be full circles or simple semicircles pointed inwards.
Even without building upwards, the ribcage provides protection for the settlement similarly to how it once protected organs. Defenses can be strung along the bones and the interior can be fortified. Given enough time, the skeleton might appear to "grow" a new artificial skin as the empty space between ribs is filled by platforms or defensive structures.