Roman city walls impress even today through their scale and magnificence, but they remain relatively underrepresented in studies of monuments within the urban environment. This thesis explores the contribution that city walls can make to our understanding of urbanism and society in Augustan Italy. It concludes that city walls can reveal important insights into how urban space, cultural identity, political relationships and social behaviour were negotiated and defined. This research situates city walls within the context of monumental public architecture in Roman cities, providing an integrative analysis of city walls as part of the urban narrative. It argues that city walls and their gateways should be studied as a social and political statement in order to gain a proper understanding of their character and meanings. Built more for show than for protection, Augustan city walls were icons of visual dominance and cultural manipulation of the landscape. They manifested in physical form ideas of status, self-representation and civic pride. Much more than a functional defensive asset, city walls provided a symbolic and psychological frame to the urban area. City walls embodied community-specific decisions driven by practicality, ritual and ideology as part of an ordered and meaningful use of public space. They demonstrated how an urban community wished to be perceived, incorporating social and historical associations which reflected the needs, aspirations and memories of the community they enclosed. The thesis also presents a new and comprehensive collection of inscriptions from Roman Italy relating to city walls, which are analysed to investigate the power of patronage, the discharge of civic obligations, opportunities for self-promotion and the combined use of text and imagery to maximise impact and display.