The CENSE project, funded by the French Research National Agency from 2017 to 2021, aimed at proposing a new methodology for the production of more realistic noise maps. CENSE stands for ?Characterization of urban sound environments: Modelling, noise sensors network and open data?. The project relied on a dense network of low-cost sensors deployed in an experimental site in the city of Lorient (France), and data assimilation techniques between simulated and measured data. Beyond the production of physical indicators, the project was also positioned on the characterization of sound environments. The project, which is drawing to a close, has produced advances on noise modelling, low-cost sensor network technologies, data assimilation techniques applied to sound levels prediction, urban sound recognition, and perception. This first presentation, of a series of five, will give a general overview of the project comprehensive approach and framework, and its operational outcomes