The original house was badly damaged by a fire. We could save only part of the foundation and we had to stay within the original first floor footprint for several reasons, for the rebuilt.
We accepted that constraining and boxy perimeter, a rather traditional envelope but leveraging on the fact that the city didn't count double height space as livable floor area, we “emptied” that cube, by distributing the second floor spaces on the perimeter and emptying the core of the house, but for a circular stair cylinder with a compound radius, and bridges connecting the second floor rooms.
This afforded plenty natural light cascading from the skylights over the center stair and large front and back two story windows.
Vertical slots in the stair cylinder allowed light to also travel toward the other sides of the first floor.