The construction of cathedral Notre-Dame de Paris sheds new light on the use of iron and lead in the building. It encourages one to question the evolution of practices related to these metals over the centuries. On the one hand, the restoration work has brought to light various armatures, chains and series of iron staples that were previously unknown, the study of which makes it possible to specify their role in the structure of the building, their chronology, but also their quality and origin. Research is also being carried out into the various uses of lead (roofing, decoration, sealing, etc.) and the practices of craftsmen at different times. The identification of the lead sources is carried out by means of elemental and isotopic analyses, making it possible to highlight recycling practices, as well as to trace the lead possible contribution to the pollution of the environment. An interdisciplinary research group on metal bringing together archaeologists, archaeometers, chemists, art historians and heritage specialists has been set up within Notre-Dame scientific research program to jointly address all these issues.