Rats have lived with humans since the beginning of agriculture. Rats have also been studied by scientists in laboratories around the globe and we know quite lot about them. Nevertheless, we do not really know what they are doing when they live wild in city parks, sewers and tunnels, in their evolutionary new and ever-changing habitat. Our research project aims to uncover the spatio-temporal variation in rat populations, how rats share and spread parasites and pathogens and how humans feel and think about rats in urban setting.