By examining the great economic and political transformations of our time, Juan Luis Manfredi-Sánchez reveals how cities and their hinterlands have become part of globalisation. The global city has joined the group of actors who develop diplomatic, political and communicative action in a manner that is de facto and lawful. Thus, the city is involved in the formulation of foreign policy at the same time that it proposes its own political agenda, which may or may not be aligned with its own country. The city thereby becomes a source of innovation in the field of diplomacy. The Covid-19 pandemic is accelerating the political and diplomatic role of cities, which have become epicentres of prevention and response in the face of this public health crisis.