The intellectual career of Giovan Girolamo Carli (Siena, 1719-1786) represents an emblematic case of 18th-century erudition, though one that was also entirely original. After early teaching posts in Colle di Val d'Elsa and later Gubbio, Carli, during a brief return to his native parts, compiled a compendium of Sienese art that would play an important part in the reappraisal of the Middle Ages which was entrusted to the more mature pen of Guglielmo Della Valle by way of his friend Giuseppe Ciaccheri. Carli subsequently obtained the prestigious post of secretary of the Royal Academy of Sciences, Letters and Arts in Mantua, during which time, stimulated by contacts with leading intellectuals, he had the opportunity of visiting archaeological excavations in the local area and creating the Galleria di Marmi Antichi, which remained substantially unaltered until 1915. The present essay retraces the inventory of Carli's private collection taken from the manuscript conserved at the Biblioteca Comunale degli Intronati in Siena in various drafts, datable to 1782 and accompanied by a detailed estimate of value in view of a possible sale, although it is more likely that the collection was in fact dispersed. A Catalogo delle mie antichità, e altre galanterie diverse, documenting Carli's antiquarian passion for accumulating objects and ornaments of various kind (natural products, mirabilia, Etruscan and Roman artefacts, engravings, paintings, carved gems and medals) and giving us an idea of the original display, based on aesthetic and typological criteria. What emerges is his tireless devotion to the work of classification, an expression of his heartfelt responsibility for an ideal inheritance to be transmitted – in a spirit of enlightenment, though already with a touch of romanticism – to future generations.