Green heritage, green history and green planning

The value of historical districts, especially in large urban contexts, is a complex issue. The theoretical debate on the extension of the heritage concept goes back to the International Conventions of The Hague (1954) and Paris (1972) and, in Italy, to the Franceschini Commission of Inquiry, and has recently even reached the hypothesis of "tout-patrimoine" (Heinich, 2009). However, theory is not adequately reflected in practice and the discussion on heritage conservation and enhancement almost never combines the urgent and topical issues of urban resilience and adaptation to climate change, thus forgetting the active and substantial role of heritage in sustainable development. Urban historical districts are among the areas most vulnerable to the risks of climate change and urbanization pressure, but urban resilience and Green Infrastructure (GI) strategies systematically exclude them. The reasons may be the lack of transformable space, the many constraints of cultural protection and the peculiarities of these contexts that are not compatible with standardized and generic strategies. Actually, a systematic inclusion of heritage aspects in urban planning debate, as stressed in art.8 of Faro Convention, is still not present. Thus, the ratification of the Convention is an opportunity to actively bring back the focus on the deep roots of resilience and sustainability that intrinsically lie in heritage. For instance, concerning urban reforestation and re-naturing processes for adaptation, it is often neglected that historical centers preserve traces of gardens and parks that are fundamental elements of the existing GI. Moreover, it is possible to reconstruct the green history of these contexts, to understand the relationship over time between the man-made environment and the natural one and draw useful hints to set future green strategies (coherently with art.9 of Faro convention) which should be appropriate for each historical area. In this interdisciplinary approach ‒that combines architecture, history and landscape‒ it is also essential to emphasize the key role of active citizenship. Founding the resilience of historical districts on historical-cultural specificities cannot disregard the need to increase awareness about the role of (green) heritage and the integration of traditional and informal knowledge that is the substrate of the city. The case study of Milan (Italy) highlighted precisely how the private green of the inner courtyards is a fundamental asset for the city and essential potential for future adaptation, stressing the need for a close dialogue between public and private