Data – big or small – is increasingly changing the perception and reality of our cities. On the one side, the opportunities look promising: better communication facilities, more efficient mobility and production by means of data based infrastructure. On the other side, we are facing various challenges and insecurities: What are the consequences of data based technology for the spatial, cultural and political future realities of our cities? Who is using or misusing data? Who benefits from data? How much access to data do we have?