This book presents the rise and decline of the meta-concept of transparency in architectural theory and practice, from modernity to hypermodernity. It investigates the complex relations around the see-through aesthetic, and the role of unseen and invisible structures for staging transparency as the dominant optics of modernity. It also examines diverse theories and tactics regarding transparency, and tests the concept in a range of works, both built and written. As such, the book introduces readers to new perspectives on space, and to processes for understanding and designing architecture, informed by media-philosophy.