[myBrain]

So yeah, it's the first rendering we saw, but it looks like it has more of a curve than you could see from that set. There's a protrusion from the SW corner that sweeps back and up, narrowing the lower segment as it rises, but then the upper segment actually goes from narrow to wider toward the south on the upper floors. The point of the roof structure follows this curve.

This one, like the sail, is going to be hard to wrap your head around until we see some better renderings / 3D models.