This project in Sherman Oaks, California, began with a 1,200-square-foot excavation carved out of seemingly uninhabitable space beneath an existing post-and-beam residence on a hillside site. The terraced solution satisfies strict code requirements that inhibit altering the existing structure. The new extension joins the living quarters above to the garden below, creating a contemporary escape, refuge, and oasis under the existing home. Angled walls, multiple floor planes, and manipulated white wall planes provide a theatrical backdrop for our client’s art collection. The large gesture of the cascading stair connects all the floors of the multitiered space, creating a unified whole. The stair, wider toward the center and narrower at both ends, creates a forced perspective. Experientially, this results in altered perceptions as one ascends or descends the stair, with the angled wall transforming into a soffit overhead. The floating form reinforces movement through the space and contains the mechanical and sound systems.