This book is the first to closely examine the location of the earliest purpose-built Christian buildings inside the city of Rome in their contemporary context. It argues that some of these were deliberately sited by their builders so as to utilise prominent positions within the urban landscape or to pragmatically reuse pre-existing bath facilities for Christian liturgical practice. Several examples are discussed with the latest archaeological discoveries explored. Two particular case studies are also examined within the Subura area of the city, and their urban location is examined in relation to the commercial, religious, social and public spaces around them, known through a 3rd century A.D. survey of the city. Certain other Christian basilicas in the city encroached or blocked roads, were situated by main arterial highways, were located on hills and eventually reused prestigious public buildings. Other examples were located by potent ‘pagan’ sites or important places of public congregation, with two structures suggesting the political astuteness of a 4th century pope. This book shows that the spatial Christianisation of Rome was not a random and haphazard process, but was at times a planned project that strategically built new Christian centres in places that would visually or practically enhance what were generally small and modest structures.