My research project examines how cities and citizens enact their relationship to nature through their multiple practices towards rats. The long shared history between rats and humans has created an abundance of reactions, narratives, symbolic meanings and practices regarding rats. Whether it is lab rats, pet rats or city rats, they are variously framed to be useful and convenient, smart and cute, and dirty and disposable. In a first part called "making rat", I explore how rats in cities have been framed in their relationship to humans and nature. Inquiring into the history of dealing with rats in the city of Zurich as my case study, I use official documents and interviews with historians to reconstruct the discursive frames and social practices which have made and placed rats in their relationship to humans. Second, I study how rats exceed human efforts of managing and controlling them. In that part, called "being rat", I try to see the city like a rat. This means following them to the places they appropriate, continuously transgressing the physical boundaries and social framings humans have established for them. Field observation and interviews help uncover rats' interactions with infrastructure, waste and humans. In a final part, I investigate what a politics of a post-dualist urban nature could look like. Looking at ecosystems in three different cities (Zurich, London, Vancouver), I use field observation and interviews with city planners, policy makers, ecologists and residents to discover their reasoning for and against an inclusion of rats, and other undesirable elements of ecosystems, in the urban environment. As such, the project extends the purview of urban ecology research to the often neglected, unwanted species that, however, form an integral part of urban ecosystems. This is particularly important in view of the resurgence of urban greening initiatives and a general "retour à la nature" in cities around the world, typically promoting sanitised visions of a green, enjoyable nature.