If there is a place where practices of "living together" have grown, between failures and experiments, this is the space on the border between cultures and peoples, lands and waters. Starting from the issues of the "public city", the research by design developed by the urban planning school at the University of Trieste crosses different perspectives and tools. With a focus on the border territories in our region, the aim is to address the regeneration of fragile lands, small and medium-sized urban centres, that are similar to many other European contexts.