In the vision of the moral philosopher Seneca, the city had a moral geography. Different areas, different buildings and monuments, each carried their own charge, on a scale ranging from virtue to vice. Considerable progress has been made in recent years in learning to measure the emotive and ideological charge attached to imperial monuments.2 Yet the investigation has been in a sense one-sided, as if only imperial monuments were ideologically charged, set against a neutral background of ordinary, uncharged, urban landscape. The aim of this paper is to use Pompeii to suggest that Roman urban landscape was differentially charged overall, so that for every area of positive charge there must be an area of negative charge set against it. This paper serves a double purpose. Pompeii as a site offers the historian incomparable opportunities for engaging with central aspects of Roman social and cultural life. Yet, for a variety of reasons, historians are too inclined to write it off as a trite and unusable source of evidence. Before turning to the moral geography of Pompeii (p. 43), I wish to offer some observations about the difficulties and potential offered by the site.