This project revolutionises our understanding of Rome and its place in cultural change across the Mediterranean World by mapping political, military and religious changes to the Eastern Caelian from the first to eighth centuries. The programme offers multiple gains for archaeologists, historians, topographers and geographers by documenting both the mundane and monumental elements of the city fabric in chronological, geographical and ideological relationship to one another. From the extravagant horti, the houses of elite families, through successive imperial palaces to the seat of papal governance the area’s architecture embodied changing expressions of political power. From the early military stations, through the grandeur of the barracks of the emperor’s horse guards, to the building and rebuilding of the Aurelian Walls, it reveals notions about the intersection of security and military power. From the shrines of the early empire to the world’s first Cathedral, it attests successive religious regenerations. RomeTrans has three objectives: first, it determines the appearance of the buildings that drove these changes, producing academically robust visualisations, appropriately contextualised. Second, it brings these elements together to model the five transformations that saw the Eastern Caelian reshaped to meet the needs of shifting political, military and religious ideas. Third, it provides a longer-term interdisciplinary perspective on the changing shape of this pivotal area than any previously attempted. All this requires a survey of unprecedented scale and sophistication, demanding a new methodology for complex urban areas capable of transforming research in historic towns worldwide. Integrating documentary sources, architectural analysis, investigation of 11 sub-surface excavated areas with the largest geo-radar and laser scanning surveys ever conducted in Rome, the project transforms our approach to the city and its relationship to the wider world.