As mobile phones are becoming ubiquitous machines with increasing processing power, this talk will focus in presenting an experimental application, CitySkin, which relies on mobile phones for data retrieval with mapping purposes. This mobile visual system provides an accessible mean to design an invisible skin of a city (an image-map output) following a user point of view at a given moment in time. This project explores relations between subjectivity and raw data by combining hard data with and visual mapping. Cities and their intrinsic diversity can be compared; as well as slight differences in the input variables can present greater changes in a recurrent path. CitySkin records the mood of a specific derive, discussing the cultural implications on computing and the design of its ubiquity.