This article explores empirical and objective approaches to combinations of non-residential activities in contemporary urban settings. The research measures the mix of uses in compact cities through the analysis of an urban fragment of Barcelona with high population density that is strolled around daily by thousands of tourists and intensified by a unique combination of daily services, commercial uses and productive activities. The resulting cartography offers a parametric interpretation at the scale of plots, blocks and streets, and establishes some tools to better understand the spatial relations of urban functional mix and proximity.