Architecture, Building and Structure Design RO54 Single-Family House by Arshia Mahmoodi RO54 is a single-family house built on a hillside site in Los Angeles. The house uses a split-level layout with staggered floor plates arranged around a central void. Central bridging stairs bring sunlight and visual connection to the deepest level, which reduces the physical and psychological distance between rooms. The outer shell was CNC milled from a digital design and follows streamlined automotive forms. A 16 foot cantilever on the second floor forms an entrance canopy. Open floor plans allow furniture to be rearranged.