The intention of this chapter is to deepen the understanding of the role of music and sound in forms of tactical re-appropriation of public spaces in its emotional, atmospheric and symbolic strength, as well as the affective role of the sound as dispositive of boundary construction. The chapter presents ethnographic research conducted in Milan, and specifically a focus on the daily use of the underground station of Porta Venezia. Diverse groups of young people use an area in the station as a place to dance, from breakdance to ‘neofolk’ dance of Caporales and, daily, they re-invent the space with unplanned uses and activities. The affirmation of these practices is considered as the construction of an interstitial territory and analysed in its auditory dimension. The alteration of rhythms and aesthetics shapes an alternative and unexpected use of bodies in the space, which constitute a spatial territory, both material and imagined, that can be read as an embodied and resounding form of heterotopia.