While two-dozen cathedrals with medieval copper-alloy doors remain in Europe, the Duomo at Monreale – the cathedral of Santa Maria Nuova (Figure 1) – is the only one in Sicily and the only one with two sets of doors, rather than just one (Figures 2 and 3). These doors lend an air of grandeur to what is now a relatively minor urban centre, an aspirational element that signifies the Mediterranean ambitions of the later Norman kings who controlled Sicily in the twelfth century. Over the course of the second half of the eleventh century the Normans established a kingdom that extended from the area around Naples in the southern Italian peninsula to Sicily, at times stretching even to North Africa, and lasted until almost 1200. It actively challenged and competed with major Mediterranean empires of the time, such as the Byzantines and the Fatimid Caliphs. As part of this effort, the Normans developed a visual and material vocabulary of power and wealth that avoided association with other Latin European groups by invoking cultural elements of the major eastern Mediterranean powers. Norman kings commissioned a range of objects in this uniquely Sicilian style, from palaces to garments to coins, but it is in objects such as monumental copper-alloy doors that this style most clearly encompasses the materials used in addition to the motifs. Starting in the early eleventh century, copper-alloy doors similar to those of the cathedral at Monreale proliferated throughout Latin Europe, conveying the power of the kings, bishops and abbots who commissioned them through their artistic ambition and their invocation of ancient themes. Thus, when the Norman king William II (r. 1166–89) commissioned the Monreale doors, he drew upon an existing trend but also incorporated distinctly Mediterranean elements that would communicate Norman sophistication to an audience that included Byzantine Greek and Muslim peoples as well as Latin Christians. While scholarly attention has rightly focused on the iconography of the doors, this essay will argue that, for their Mediterranean audiences, the doors’ copper itself played a critical role in the symbolic power of Monreale because of the material's complex connections with wealth, learning and technology.