Precious metalwork, relics, chess pieces, ostrich eggs, unicorn horns, and bones of giants were among the treasury objects accumulated in churches during the Middle Ages. The material manifestations of a Christian worldview, they would only later become naturalia and objets d'art, from the sixteenth and the nineteenth century onwards, respectively. This book traces the origination, development, and later history of church treasures, and explores the form and function of these objects of memory. They were a source of wonder for their contemporaries and remain so today, albeit for quite different reasons. Indeed, our fascination relates primarily to their aesthetic qualities and the meaning that we assign to them. Dealing also with this paradigm shift, this study opens up new paths toward a real archeology of current historiographical and museum practices.