En Obra is a graphic memory of Mexico City that portrays the rise and decay of its modernization project through the collection of the Museo Archivo de la Fotografía. What we see here is the material of a little explored, almost unpublished, archive which was protected for several decades. In it, we find images that range from the registration of infrastructure works such as water, drainage, paving, and lighting, to the transformation of public markets. It offers a look at reformatories, prisons, hospitals, fire stations, driver education programs and traffic police actions. It also shows many of the symbolic elements of power: its monuments and civic rituals. Thus, this book constitutes a self-portrait of the State in which the history of the governments of the city and the birth and evolution of the urban trace intersect with the transformation of the daily life of its inhabitants.