"Considering the scale of the ecosocial challenge, we have to look towards territories and cities, since they are the key centres of the social metabolism and they concentrate the transformative potential of citizens with the capacity to bring about profound ethical, cultural, political, and socio-economic changes... We need to reclaim what the secretary general of the 2012 Earth Summit, M. Strong, declared in the closing session: the (global) sustainability battle will ultimately be won or lost in cities." -- from The Critical Crossroads