Public Transport (PT) represents the backbone for the development of sustainable mobility in urban areas. However, PT is often underutilized in many European cities; thus, tools supporting stakeholders and local authorities are required for the assessment of its performances, as well as for the design of effective strategies for its development. Several metrics are usually adopted to evaluate PT. However, these metrics can be useful if related to points of interest generating/attracting commuting trips, business trips or any other trip necessary for satisfying the mobility needs in an urban area. This requires a satisfactory knowledge of the transport demand or the identification of these points of interest. This study proposes a framework for identifying zones with a high potential of attracted travel demand (hereinafter called as Relevant Zones - RZs) in a city. The framework has been applied to the city of Rome (Italy) exploiting Open Street Map and additional open source layers about points of interest, together with socio-economic data and the land cover: it resulted in the selection of 92 zones (out of 1,186 traffic zones) validated through the comparison with attracted trips by Floating Car Data (FCD).