The bronze doors that survive to this day are the only complex of monumental bronzes from the European Middle Ages that has survived intact. Most of them date from the 11th and 12th centuries and are located in Italy. The doors were crafted from a variety of copper alloys using the lost wax process. They could be cast as a single unit or individual metal fittings could be attached to a wooden support. Some doors feature inlays of various materials, which allowed for the coloured depiction of different biblical scenes or saints. We can now answer questions about the manufacture, the choice of materials and the significance of the materials of all the doors on-site thanks to a complete high-resolution photographic documentation, 3D models and comprehensive material analyses. This book presents the latest research on these extraordinary objects, showcasing new findings and insights.