A study of the different local processes by which late-medieval southwestern Europe embraced punitive imprisonment as an opposite means of safeguarding its basic social and religious values. I trace the religious, social, economic and political structures which enabled penal incarceration to proliferate particularly in an urban environment, and relate in what ways the prison became engrained in contemporaries' political thinking, embedded in their concepts of justice, sovereignty, and social marginality, and integrated as a sine qua non of their urban space. To those who consider the prison as axiomatic to western penology, this study underscores both the contingency of institutional development and the potential variety of its social, political and even religious functions in different contexts. Archival research will focus on northern Italy, one of three politico-geographical units which saw the near-simultaneous advent of punitive imprisonment. The dissertation as a whole will also deal with the Inquisitorial prisons of southern France, and will adopt a comparative approach towards English imprisonment practices. Its main contribution, however, will be to fill the scholarly lacuna of the Italian peninsula, home to a proliferating urban culture unparalleled in variety and autonomy throughout late-medieval Europe. Despite an abundance of records, Italian historiographical emphases led to a general neglect of the topic, which lends itself to the study of social, legal, political and religious history of the late Middle Ages.