A “real-time” noise mapping project, named DYNAMAP, has been developed in the framework of a Life+ 2013 program and cofunded by the European Commission. The project aims at giving a real picture of the noise generated by vehicular traffic. To this purpose, a dedicated platform has been developed to elaborate the information from distributed noise monitoring stations. The methodology has been implemented along the ring road encircling the city of Rome (Italy). A detailed description of the system is given together with a report on the testing campaign that allowed evaluation of the accuracy and reliability of the system. From the monitoring campaign satisfactory results have been achieved, showing an average overall prediction error of ~1.5 dB.