The contributions to this publication reflect not only the geographical range of the topic, but also different methodological approaches. The authors have deliberately chosen different focal points, which complement each other. The methodological spectrum ranges from metrological studies of insula grids to the application of Space Syntax Analysis and aspects of Household Archaeology. The contributions are based on various sources, ranging from antiquarian research in excavation archives and the re-evaluation of older excavations to current surveys, rescue and research excavations. The geographical and content-related diversity of the examples presented in the volume allow for a comprehensive comparison, highlighting differences and similarities. Altogether, the publication aims at investigating what an insula was and how it functioned in a larger context.