The objective of this article is to introduce the functions of the Iron Museum of Nancy. All metals--with the exception of gold-- deteriorate if left in the soil for centuries. Generally, they deteriorate further once they are excavated and displayed without undergoing complex treatments of preservation. Thus, many metallic artifacts exhibited in museums have suffered severe damage. The Nancy laboratory operates on four fronts: it treats metallic objects, does research on metallurgical techniques used in ancient times, improves and codifies the methods of treatment, and trains interns and organizes classes and conferences. Ancient metal objects uncovered during a dig undergo three distinct processes: cleaning or stripping, restoration, stabilization-preservation. Scientists and curators work as a team, so that the human context --i.e., the historical authenticity--of the object being restored will not be overlooked. The Nancy laboratory is renowned in this respect. (Nancy is the ancient capital of the former Duchy of Lorraine, in eastern France, known for 18th C. ornamental iron gates)