City-regions have gained economic and political power in the process of globalisation. Many of them use this power to develop their own international activities. This book investigates why city-regions go global and the consequences of their newly gained self-confidence on the international scale. The book analyses Swiss and EU city-regions' international activities with seven in-depth case studies. The book shows that the local economic setting, and the political response in developing international activities, are closely linked. Not only has urban politics changed due to its international dimension, but also the interplay between the core city, the agglomeration communities, the regional, the national, and EU levels. Understanding the role of the EU in city-regions' international activities is crucial for comprehending recent trends in urban governance.