To date, critical examinations of smart cities have largely ignored their temporality. In this paper I consider smart cities from a temporal perspective arguing that they produce a new timescape and constitute space-time machines. The first half of the paper examines temporal relations and rhythms, exploring how smart cities are the products of and contribute to space-time compression, create new urban polyrhythms, alter the practices of scheduling, and change the pace and tempos of everyday activities. The second half of the paper details how smart cities shape the nature of temporal modalities, considering how they reframe and utilise the relationship between the past, present and future. The analysis draws from a set of 43 interviews conducted in Dublin, Ireland, and highlights that much of the power of smart urbanism is derived from how it produces a new timescape, rather than simply reconfiguring spatial relations.