Electro-Magnetic Radiation (EMR) measurements were carried out in the urban region of Mytilene town sited on the east side of Lesvos Island, Greece. More than 50 measurement points were recorded in accordance to a pre-defined measurement plan based on a GIS. All possible sources of background EMR were investigated, namely in the frequency area between 9 KHz – 1.5 GHz. Point values were organised as measurement network-points on a generated digital map of the surveyed area. Network point values were also used to produce a digital map of background EMR in the town using GIS software. EMR measurements are time-depended according to the operation scheme of nearby existing base stations. To avoid severe time-bias, several repeated measurements were carried out in every point from which the average value was finally employed. The produced digital map could be considered more-or-less adequate of the actual background electromagnetic field in units of electric field strength (V/m). Since the distribution of EM base stations varies progressively due to new installations, power-density changes and other technical causes, maps delineate profiles adequate only for restricted periods near the measurements. Due to this fact, different scenarios were introduced accounting for potential differentiations in the existing EM base stations network, as for example regarding their power and site. Putting their new characteristics on existing map GIS software, alternative background map were reconstructed according to the new conditions. This work is very useful for policy makers because it offers a scientific basis after an initial EMR background record, then every new installation could be checked out from the developed software. This could be a significant tool for over monitoring taking into account the promulgated rules and limits for EMR. Demonstrated map shows points and neighborhoods of high electric field values up to several V/m. Measurement points were selected, if it is possible (regarding free area from high constructions) near schools, kindergartens and playgrounds. Findings were impressive for such a small town and alarming for new installations.