To recover, revitalize, convert—these actions have become increasingly present in contemporary cities, where architecture takes on the role of stitching together the overlapping layers of time that make up the urban fabric. Faced with this task, architects have explored a range of design strategies. Among them, one material in particular has stood out for how frequently—and effectively—it appears in interventions on historic buildings and contexts: corten steel. With its rusted surface, rich in texture and tone, it seems to offer a compelling answer to the challenging question of how to insert the new into the old. But what makes this material so recurrent in these situations? Is it simply its durability and versatility, or is there something deeper in its visual and symbolic presence?