As urbanisation has come to characterise contemporary societies, large cities have become quite ambivalent places for the human species: they are removing the human body from its perceived natural condition, while increasingly attempting to provide a cure for the ills of a sedentary life. Fitness gyms are presented as the ‘natural' solution to our ‘unnatural' lifestyle as urban dwellers and as a therapeutic fix to the ills of metropolitan living. This paper deploys a mix of qualitative methods (ethnographic observation, interviews and discourse analysis) to explore fitness culture as an urban phenomenon. Using data from Italy and the UK, it develops a micro-sociology of the spatiality of the gym that helps to approach this institution from within, deconstructing those claims which contribute to its cultural location as a key ingredient in contemporary urban lifestyles. The paper first looks at how fitness culture is negotiated through the marshalling of structured variety within the spatiality and temporality of gyms. It then explores the specificity of fitness as urban, instrumental leisure as compared with other forms of active recreation or sports available in urban contexts. It finally considers, on the one hand, the way in which fitness activities are continuously renovated, drawing on the fields of both sport and popular culture and, on the other, the kind of subjectivity and embodiment that fitness culture normatively sustains.