Beatriz Colomina, Professor of Architecture and Founding Director of the Program in Media and Modernity at Princeton University, discusses how modern architecture, launched by an international group of avant-garde architects in the 1920s, has usually been understood in terms of functional efficiency, new technologies of construction, and the machine aesthetic. In contrast, the hypothesis of her research is that the architecture of the early twentieth century was shaped by the dominant medical obsession of its time: tuberculosis. Colomina’s project investigates architectural discourse and how it has, from its beginning, associated building with body. The body that it describes is the medical body—a body that is reconstructed by each new theory of health. Avant-garde architects of the early decades of the twentieth century presented their new architecture as a health inducing instrument, a kind of medical equipment for protecting and enhancing the body. Buildings even started to look like X-rays revealing internal secrets.