•Advantages of integral planning of recreational areas for urban population on both sides of the Italian-Slovenian border.•Landscape ecology findings support the preservation of the spatial distribution of key urban green areas.•Urban forests, parks and green corridors form an indispensable pattern of a green urban network connecting both cities.•Old maps and satellite images are suitable tools in defining the primal structure of forests. The provision of health and well-being is one of the fundamental tasks of urban green infrastructure. This requires a new estimation of the strategic distribution and accessibility of green areas. Gorizia and Nova Gorica are two cities lying next to each other on either side of the border between Italy and Slovenia. Due to political circumstances, they developed independently, which applies to their green areas as well. Urban city areas and other land cover classes were extracted from the CORINE Land Cover map; the digital data were processed using ArcGIS. At the landscape hierarchical level, the importance of natural vegetation remnants was assessed based on current land use maps. Forest patches, hedgerows, remnants of natural vegetation, and spontaneous afforestation on abandoned agricultural lands were detected and delineated using CNES digital images and digital orthophoto images. The green areas positioned in the two interior city areas were delineated separately according to data on the two cities’ green areas. We estimated the forest continuum separately, based on the oldest cartographic sources from the end of the 18th century, the Franziscean cadastre from the early 19th century, and the Italian cadastre from 1940. We estimated the interior or core area of the forest patches based on studies of habitat fragmentation and the depth of the forest edge. Our research theory is based on the proven sustainability of indispensable spatial patterns emerging from landscape ecology that are especially necessary in altered (rural, urban) landscapes. Our results show that the most important pattern of green areas supporting the well-being of both cities’ inhabitants can be achieved by the mutual development of the two major urban forests, each situated in one of the cities, in addition to riparian corridors and bits of nature represented by public parks. Collaborative planning between the two cities would enhance common benefits, including future economic and social influences and innovations.