The complexity of cities (a diverse and always changing environment) produces a huge amount of data. The growing availability of tools to generate, capture, store, manage and analyze this data opens up a wide spectrum of possibilities around those big data. The opening up of public data (public transport, traffic flows, water, waste, use of space, business, etc.) offers the possibility of transforming them into far more useful information than just messy and purely statistical aggregation. The result of this in a context of wide spreading of mobile devices helps to understand the social value of creating new apps that use this data to give users greater ability to interact and experience the city from their own needs. Visualization has become a expanding tool in recent years.