A polymath, Eugène-Emmanuel Viollet-le Duc (b. 1814–d. 1879), is best-known today as a restoration architect and champion of the Gothic style whose influential theoretical writings on form and function collected in the ten-volume Dictionnaire raisonné de l’architecture française du XIe au XVIe siècle (translated loosely as The Foundations of Architecture; 1854–1868) and the two-volume Entretiens sur l’architecture (Lectures on Architecture, 1863–1872) exerted a profound influence on modern architects such as Victor Horta, Antoni Gaudí, Louis Sullivan, and Frank Lloyd Wright. An independent thinker who refused the normal French path to architectural legitimacy—training at the École des Beaux-Arts—the talented draftsman took advantage of his personal and family connections—including Prosper Mérimée, Ludovic Vitet, Baron Taylor, Jean-Jacques-Marie Huvé, and Jean-Baptiste Lassus—to obtain the knowledge, training, and commissions that would transform him into the preeminent 19th-century French restorer of monuments. Much criticized in the 20th century for having intervened too aggressively in well-known restoration projects such as the Church of the Madeleine at Vézelay, the cathedral of Notre-Dame de Paris, and the walled city of Carcassonne, the increased accessibility of archival sources has allowed 21st-century scholars to reassess his entire body of work, setting his voluminous writings and correspondence against the intellectual, cultural, and administrative context of his time, a period in which Viollet-le-Duc and other self-trained specialists laid the foundation of what would become the academic field of medieval studies. His restoration theories and influence have been well studied since his death, but his many complementary activities, particularly his prolific attempts to popularize architecture and history for the masses, have yet to be systematically explored in any language. Viollet-le-Duc was not just one of the first historic preservationists, he was also a talented draftsman, archaeologist, architect, engineer, public administrator, teacher, theatrical set designer, international exposition organizer, city councilor, journalist, children’s book writer, military strategist, and ecologist.