From 14.3. to 16.3. 2017 the Technical University of Civil Enginnering in Bucharest hosted the final conference of the European COST Action Sub-Urban, which was focused on creation of 3D geological models of the urban subsurface and their inclusion in the land use planning process. Sub-Urban is a network of Geological Surveys, Cities and Research Partners from 31 European countries. The results of this action include a considerable amount of the best practices examples from 13 European cities and a toolbox that should serve as an inspiration and help in the process of city planning. The project team hopes that the toolbox will help to raise the awareness between urban planners and geologists and to provide the decision makers with tools that will lead to informed decisions and a sustainable use of the urban subsurface.