Eugène Viollet-le-Duc is one of those architects who took an interest in science. His biography shows that, from a young age, he practiced arts and natural sciences. As a result, his love of landscape painting was related to geology. Throughout his career, he made analogies between architecture and living organisms. For instance, he compared his idea of architectural restoration to a paleontologist’s approach trying to piece back together an extinct animal. Looking at his library, however, shows that the scientific books he owned were rather general, except for the field of alpine geology, for which he took a particular interest. Yet this very interest was strongly defined by the objec- tives of the Club Alpin Français, which aimed at preserving and developing this natural heritage. Both romantic and positivist approaches were thus intertwined in Viollet-le- Duc’s scientific culture.