Technologies have created crucial connections across borders requiring new forms of regulation. This book analyses how experts, cartels and international organizations have written the rules for Europe since around 1850. Based on fresh research in the archives of multiple international organizations and European countries it explores the ‘hidden integration’ of Europe – forms of integration that were not always visible, but affected the citizens of Europe in their everyday lives. Richly illustrated and engagingly written, the book de-centers the present-day European Union in a new long-term understanding of European integration.