Immaterial Architecture (London and New York: Routledge, 2006) is a 70,00 word authored book. Architecture is expected to be solid, stable and reassuring—physically, socially and psychologically. Bound to each other, the architectural and the material are considered inseparable. But Immaterial Architecture argues that the immaterial is as important to architecture as the material and has as long a history. Immaterial Architecture explores the often conflicting forces that draw architecture towards either the material or the immaterial. It discusses the pressures on architecture and the architectural profession to respectively be solid matter and solid practice, and considers concepts that align architecture with the immaterial, such as the superiority of ideas over matter, command of drawing, and design of spaces and surfaces. Focusing on immaterial architecture as the perceived absence of matter more than the actual absence of matter, Immaterial Architecture devises new means to explore the creativity of the user and the architect. The user decides whether architecture is immaterial. But the architect, or any other architectural producer, creates material conditions in which that decision can be made. In conclusion, Immaterial Architecture advocates an architecture that fuses the immaterial and the material, and considers its consequences, challenging preconceptions about architecture, its practice, purpose, matter and use.