Acknowledging the many processes of regionalization of international law underway worldwide, and their promises and perils, this year's lecture focuses on the international law of regions, and how to build a world of regions. The title is a double-entendre: it will deal both with the international law that regions help to adopt, interpret and/or apply (e.g. regional customs and exceptions), and with the international law that institutes and orders regions in various forms (e.g. regional organizations, regional groups within universal organizations, regional courts). The lecture and seminar will address various sub-questions, such as the tension between universality and regionalization of international law, the relationship between regionalism, federalism and imperialism in the reconstruction of the international institutional order, the international rights and duties of sub-national and transnational regions, and the role of civilizations in comparative international law. Some of these themes will be taken up again, along with many others, in this year's seminar.