Cities today are intricate hybrids of physical and informational space. Brought into being through complex yet common everyday techno-social practices, these hybrids rely on the wireless spectrum to enable a variety of media, information, and communications events that continually make and remake the spatial conditions of urban life. This paper examines the relations between this Hertzian space and the architecture of urban environments. Building on a longstanding discourse surrounding the material and immaterial limits of urban architecture, it asks how we might begin to think about shaping the Hertzian space of contemporary cities through the practices and promises of urban computing and locative media. Coaxing architecture beyond its professional and disciplinary boundaries and, at the same time, recasting contemporary media art within broader social, cultural, and political contexts of urban space, the essay attempts to outline a conversation between these fields of practice that share a common theater of operations: that of the contemporary city.