Cities are data rich environments, the aim of the Data Walking research project is to explore this 'data space' through walking with environmental sensors, each walk cutting a path or transect through the 'data space'. The ubiquity of smart phones, low cost micro controllers and environment sensors, open-source hardware and software, empowers anyone to gather data on the world around them. This technology enables a designer to work end-to-end from data gathering through analysing, editing, authoring and visualising. The act of doing brings about greater insight. A further strand to the project is to create experimental visualisations and maps across a range of media from physical to printed to interactive. Data Walking is currently gathering data from the North Greenwich Peninsula in London. Previous project phases have looked at Amsterdam, New York, and East London. Data Walking has been exhibited at the Barbican Centre, London, as well as featured conference presentations at ITVC visual communication conference, Thessaloniki. There are many outcomes from this ongoing research project, from 3D printed sculptures, video, experimental maps and visualisations in interactive and digital forms.