Cities have contributed for centuries to the promotion of some of humanity’s greatest ideas, we must now urgently include them as among the principal players in the environmental debate and at the forefront of any policy tackling climate change. Nevertheless, even today one of the most significant technologies capable of absorbing CO2 and restoring our environment is photosynthesis. Planting trees, in addition to protecting, restoring and managing existing natural areas and biodiversity, together with de-carbonization, renewable energies, digitalization, smart mobility and the circular economy could be the set of tools necessary to counter the climate crisis. Today the effects of the Anthropocene age are ever more visible, changing our environment and affecting every species that lives within it. Green Obsession offers a path to be taken, a hard but still necessary paradigm shift –even for architecture and urbanism– that aims to give a voice to this much needed ecological transition. This book aims to unveil the processes and the complexity involved in the search for a new kind of urbanism, while raising questions and opening old wounds related to the relationship between the human species and Nature and finally putting these fragments together to create a portrait of our era.