Rome was defined during the early modern era as the teatro del mondo (theatre of the world) and patria comune (common homeland); these images expressed the awareness of a universalism that was not only religious in nature, but also a sign of cultural belonging and a recognition of an undisputed political centrality. The chapter on ‘négotiation continuelle’ in the Testament politique attributed to Richelieu, considered as a cardinal text of baroque politics, contains a warning that: ‘we need to act the world over, near, far, and above all in Rome’. In the city of the pontiffs, where power was manifested at the highest level, private citizens and delegations from institutional bodies and nations constantly strove to gain concrete advantages, prestige and authority. It was precisely for these reasons that Rome can be considered – to use a modern term – a political laboratory, a place where experiments were made with original ways of doing politics and where such ways were the subject of reflection and theorizing. The identification of the environments, the specific forms, the protagonists of the culture and political practices formulated in Rome still await a systematic reconstruction, despite the abundant written material on the subject, both Italian and international.