This report by Earthwatch Europe shows how urban Nature-based Solutions (NbS) are a sustainable tool for building resilient cities. The report highlights how science and community engagement can provide key answers to support a sustainable future, providing the first insights for planners, municipalities, and businesses. Through citizen science-based research, Earthwatch explored a variety of urban NbS, creating an innovative international research program that: • comprised eight research projects in 17 cities around the world focusing on local environmental issues and considering people and places. • Filling knowledge gaps on the function and management of various Nbs for climate resilience in four areas: carbon capture, flood mitigation, thermal comfort and water quality. • Provided insights into the important trade-offs in ecosystem services that NbS can provide. • Actively involved 28 local academics and 1,955 non-expert participants through Citizen Science, collecting 80,000 data points in total.