How can nature help us design and build our cities? Nature-based solutions have the potential to provide multiple benefits across a range of sustainability challenges facing cities. They can help to limit the impacts of climate change, enhance biodiversity and improve environmental quality while contributing to economic activities and social well-being. But what are nature-based solutions? Examples include green roofs and city parks that reduce heat, city lagoons that can store water as well as vegetation and rain gardens to intercept storm water. This course will explore nature-based solutions in cities in Europe and around the world. It will connect together the key themes of nature, cities and innovation. We will discuss how to assess what nature-based solutions can achieve in cities. We will examine how innovation is taking place in cities. And we will analyse the potential of nature-based solutions to help respond to climate change and sustainability challenges. This course combines both technical knowledge and the social sciences to better understand nature-based solutions in a holistic perspective. New governance arrangements, business models and financing, forms of citizen engagement and innovation pathways will be needed to make the promise of nature-based solutions a reality. In this course, we bring together a collection of diverse films and key short readings on nature-based solutions as well as interactive forums and practical assignments to create an online learning community for nature-based solution in an urban world.