This thesis explores Dublin’s relationships with horses, cattle and pigs in the twentieth century, a period of profound political, social and physical transformation. Using a ‘collage’ methodological framework involving Geographic Information Systems (GIS) technologies, oral histories and archival material, this thesis examines the locations, roles and functions, and reasons for the eventual disappearance of these animals from the city. Despite the proliferation of animals across the city identified at the beginning of the twentieth century, the spatial distribution of animal housing and animal-related businesses revealed distinct zones shaped by their presence. The impact of the animals on the rhythms of city life along with the concentration of infrastructure supporting both local urban agricultural practices and national agriculture undermines the concept of Dublin City as entirely urban during much of the twentieth century. To meet the demands of the city, the flow of animals and products such as milk into, around and out of the city emphasised the city as a ‘space of flows’ with porous boundaries which hampered the autonomous authority of Dublin Corporation. This resulted in the Corporation’s inability to effect public health improvements related to milk within the municipal district. Furthermore, the importance of animals to Dublin City’s urban ecosystem connected the city with rural Ireland, Britain and beyond and, unsurprisingly, the impact on Ireland of the major political and economic upheavals of the twentieth century directly affected the city’s animal-based urban metabolism with widespread social and economic consequences. As attitudinal landscapes were evolving alongside physical, social and political landscapes during the twentieth century, Dublin City also functioned as a network hub for modern ideas flowing into the country which informed reforming groups such as the Irish Clean Milk Society and the Dublin Society for the Prevention of Cruelty to Animals. Human-animal relations evolved as these groups successfully shaped local and national policy regarding the treatment of animals and their products. Meanwhile, oral histories and memoirs revealed that, throughout the research period, human-animal relations in the city were nuanced and uneven and strongly determined by factors such as gender and socio-economic status. Ultimately, this research contributes to the literature by revealing what has previously been overlooked by scholars of twentieth century Dublin – the importance of animals to the fundamental fabric and functioning of the city.