The research’s main objective is to explore and encourage modes of architectural practice that can foster multispecies co-living to reduce biodiversity loss and increase the quality of life for both human and nonhuman inhabitants of architecture. This is achieved through conceptual discussions, comprehensive architectural case studies and work-based design explorations that support cross-species co-living in the context of Eastern Norway (Østlandet)—a geographical region of south-eastern Norway consisting of the counties Vestfold, Telemark, Viken, Oslo and Innlandet. A pluralistic method builds on analytical, critical and work-based explorative studies consisting of two parts: (a) historical and contemporary case studies in Norway that support modes of cross-species co-living and (b) design explorations by the second author investigating the operational potential of kindness in architecture. The notion of kindness in this research is built upon an understanding of the amalgam of concepts: solidarity, kinship and being kind, explained in the article’s introduction. The potential for designing with and for nonhumans to reinvigorate modes of co-living and support existing habitats is investigated, focusing on the ways three bird species relate to a specific building in Eastern Norway due to their habitat needs in the region: Cyanistes caeruleus, Eurasian blue tit (blåmeis in Norwegian); Passer montanus, Eurasian tree sparrow (pilfink in Norwegian); and Delichon urbicum, northern or common house martin (taksvale in Norwegian). The research contributes to ongoing discussions within architectural discourse regarding multispecies inhabitation and architecture’s role in the current biodiversity crisis and provides insight into both historical and contemporary/ongoing design solutions for multispecies co-living.