Nature-In is an interdisciplinary research project that will unfold and analyse the underlying forms of knowledge behind exemplary postwar-Danish and traditional-Japanese buildings which stand out for their interior space connection to Nature, which remains unexplored, to inform us of a sustainable contemporary interior design practice.To maximize the contact with Nature in the health and wellbeing promotion of populations, design strategies are urgently needed. Despite the increasing interest in this global concern, there exists limited knowledge and research into “how to integrate Nature with our dwellings’ interior space”. There is a lack of architectural small-scale solutions for achieving this and also limited research into the ways these solutions can enable their integration. To bridge these gaps, I will conduct a case-study analysis to present the first synthetic overview, revealing what devices are used in these case-studies to link their interior space with the surrounding nature. With the involvement of a network of international experts, a methodology that links architectural research and practice, and a link to my own practice, I will provide a catalogue of potential sustainable practical devices and recommendations for integrating architectural devices of the buildings studied and I will influence researchers, design practitioners, policy-makers and society in building practice. The main aim is to effectively enhance the health and wellbeing of communities through daily interaction with Nature in urban areas of the future, an urgent challenge at EU and Global level. Nature-In is very original and innovative in terms of objectives, how it is conceived and how it will be conducted. It will open a new research branch of Architectural Design and a new phase in the Biophilic Design’s implementation for the built environment. Moreover, it will make an important contribution to the EU-knowledge base on Nature-Based Solutions, a significant step for the EU.