The most recent wave of computation in contemporary societies involves the application of new digital technologies to the public domain where the idea of automating the city and its functions has now become central to urban planning. The so-called smart city which is the label used for these collective technologies is based on the embedding of a multitude of passive and active sensors into the built environment which is producing vast quantities of data in space and time through real time streaming. This data is ‘big’ in the volumetric sense and it is also complete in that is rarely related to any sampling of these data volumes. Moreover, it is changing our conception of the city from thinking about urban changes in the medium or long term to the short term and the routine – to the hourly and daily cycle of activities – which in turn is changing the very things that we seek to plan and optimize (Batty, 2016). To an extent this also represents a change in scale for where time scale are very short, spatial scales are also shorter and this the focus is on much more local spatial environments. In this presentation, I will begin with a conceptual model of the smart city, talk about real time streaming and the kinds of sensors that are now being employed to generate new data. I will review the problems and potential of this data and the kinds of model that are need to look at movement and change in the 24-hour city. I will present some examples from our work on transit systems where there is much transit data dealing with real time streaming showing examples in Singapore, London and Beijing, and work on social media for large cities and how we develop portals or dashboards to such examples while also exploring new forms of participation, crowdsourcing and open data that are enriching the data that we have at our disposal. I will conclude with ideas about how the real time city can contribute to our understanding of longer time periods and urban change.