Pompeii exists not only in its concrete materiality in-situ and ex-situ, but also in countless adaptations and re-interpretations which shape our cities and deeply affect the modern world. This book examines the impact of Pompeian wall paintings on European architectural design and discourse during the Industrial Revolution, with particular focus on the role of the Vesuvian city as a laboratory for the creation of a new ‘iron style’. When cast iron first appeared as a building material, architects faced unprecedented challenges after millennia of stone construction: cast iron required a new language, a new syntax, new proportions and ornamental patterns suited to the characteristics of the material and in line with the functional and aesthetic standards of modern cities. In this context, the imaginary structures painted on the walls of Pompeian buildings, interpreted as a prefiguration of a light, airy, dematerialised architectural order, were adapted to the needs of the time through a process of transfer from one medium (painted surface) to another (three-dimensional structure). A selection of case studies – including works by Karl Friedrich Schinkel, Henri Labrouste, Jakob Ignaz Hittorff, and Gottfried Semper – illustrate how the so-called Pompeian arabesques, i.e. models, motifs, and ideas found in fresco paintings, were transformed into iron elements at various scales, ranging from the decorative detail to the structural support.