“…The latter are the main sites of innovative activity, the ‘incubators’ of new knowledge: cities are the principal centres of research, given their large pools of expertise and the availability of advanced services (finance and insurance) that are ready to carry the risk of any innovative activity. The fuel for continuing knowledge and innovation processes in cities consists in the density of external, particularly international, linkages maintained and developed by individuals, groups, associations, firms and institutions––what is increasingly called ‘relational capital’ (Camagni, )––coupled with a large diversity of competencies, based on which complementary knowledge can find common cognitive ground (Burger and Meijers, ; Glaeser et al ., ).…”