ISEK⁴ is a cross-border pilot project for the development of a new planning instrument in Austria. It deals with two spatial realities which -despite obvious needs are rarely considered in context in existing planning instruments: the inner city and the functional region. An integrated urban development concept for the four inner cities of Bruneck (South Tyrol), Hermagor-Pressegger See (Upper Carinthia), Lienz (East Tyrol), and Spittal an der Drau (Upper Carinthia) was designed based on a regional symbiosis as “second” level of action (demonstrating and using synergies between the inner cities, as anchor points of public life in the region). The ISEK⁴ is based on an integrated, interdisciplinary approach and was developed together with the steering groups from the cities: within eight months, knowledge and needs were collected, recorded, and located in different workshop formats.The paper will focus on the lessons learned and the transferability of the project approach and results.The project of an Integrated inner-city development concept in a regional context was initiated by the South Alpine Space City Network (bottom-up approach).The region is exploring new limits of regional cooperation and is contributing to the implementation of the EU Leipzig Charter (2007/2020) and the Territorial Agenda 2030 (2020). Key objectives of the Austrian Spatial Development Concept 2030 (ÖREK 2030) are put into practice, such as the strengthening of polycentric structures, planning in functional living spaces, as well as the climate-friendly and sustainable spatial development.These challenges can no longer be dealt with by inner cities alone. Working on selected issues regionally is not only efficient, but also makes sense. One of the basic ideas of the regional symbiosis is to further develop the inner cities according to common regional priorities. Accordingly, seven spatial guiding ideas are formulated in the ISEK⁴ for the SOUTH ALPINE SPACE. They run through all levels of the concept and are always recognizable: in the future images of the cities, in the integrated inner-city development, in the interventions for the focus areas or perspective areas as well as in the regional vision. The symbiosis shows how the spatial guiding ideas are transforming the SOUTH ALPINE SPACE in the future.The ISEK⁴ is a planning instrument for self commitment and thus opens opportunities fora spatially focused and active shaping of the future of the inner city and the entire region. The meaningfulness of regional cooperation is also reflected in the structure and conception of the ISEK⁴: Regional potentials and goals are constantly thought of in combination with local activities and trends. In the city-peculiar parts, the planning focuses on specific sub-areas of the respective city. Idea sketches provide impulses for implementation. The regional symbiosis links the four ISEK⁴ of the individual cities and raises them to the regional level. This creates an overall picture for the SOUTH ALPINE SPACE that is more and in terms of sustainable local and regional development can do more than the sum of the four concepts for the inner cities. TheISEK⁴ actively contributes to saving soil by prioritizing inner city development over outer city development. The ISEK⁴ goes one step further and pursues the strategy of bringing commercial uses from the outskirts back to the inner city. Urban qualities such as mixed use or lively ground floor zones provide flair and a high quality of life in the cities and the region. ISEK⁴ addresses all aspects that are part of a good life for all generations.