The bas-relief, from the Ara Pacis Augustae, was placed in the garden together with other artefacts of the same provenance found in 1568 and purchased in the same year by Cardinal Ricci, the owner of the land that he later turned into a rich residence. Many Roman finds were later removed, while others, including this bucranium with a festoon as a symbol of peace, still adorn the façade facing the garden.