“Authenticity” as the purportedly “original”, “pure”, or “true” character of persons, objects or practices has become a major public discourse, a powerful driver of heritage debates and cultural change and a key research issue in the humanities. From theatre and museums studies to heritage conservation and the historical sciences scholars dispute the ways in which authenticity indicates and triggers cultural change in modern societies. While there is a broad consensus among constructivist approaches that historical authenticity was and is always socially and culturally produced, and that there is no such thing as “the pure” or “the original” in terms of materiality, the case of built heritage seems to challenge this approach. Here strong academic and public controversies have emerged on the role and impact of materiality for authenticity. This project is the first to systematically analyse patterns of such discourses in a transnational historiographical perspective.