Cicero's letters have figured prominently in some of western modernity's most cherished illusions about the immediacy of its encounter with Classical antiquity. Celebrated since their discovery in the Renaissance for their intimate mode of self-expression, they have been prized ever since for the unparalleled proximity they appear to give us to the events and leading figures of the late Republic. However, they were only organized into books and collections, and published as such, by unknown editors long after Cicero's death. Modern editors have also dismantled these collections and reorganized the letters chronologically in an attempt to reconstruct the events that they document more accurately. Souvenirs of Cicero studies the narratives that the letter collections unfold and the post-Republican perspectives that shape them. It looks closely at the ancient format of Epistulae ad Familiares, the collection that incorporates Cicero's widest cast of correspondents and has been most vulnerable to this practice of reorganization, and reverses it, attending instead to the collection's status as an artefact of the later imperial age. Francesca K. A. Martelli traces the social, political, and technological agencies that shaped this letter collection in antiquity and elucidates the interests that these editorial interventions serve both for ancient readers and for our interpretation of the letters today by integrating a close analysis of these letters with hypotheses drawn from contemporary media theory. Cicero's letters emerge from this study as residual media, which haunt subsequent history with the Republic's lost futures as they circulate beyond their own era.