In the past decade, a growing strand of publications has used the concept of empire to analyze the integration process of the European Union. What does the resurrection of this old idea mean? Is it an attempt to get out of the sclerosed debate on integration, trapped between two families of integration thoeries (functionalist theoreis on the one side and intergovernmental famiy of the other side) which have not been able to impose themselves as satisfactory theories? Is it just a provocative attitude copying literature on the USA and the concept of empire? The EU is a big multinational polity with open borders, which is an atypical political system in the 21st century. Given this, which explanatory tools can help explain this political system and the challenges it faces? Which theories, models and concepts can help us tackle these issues? Should we resurrect old ideas or go for new ones and if so, which ones? Can we dig out again the federal idea? Is the concept of empire more promissing? Can it be taken seriously? The papers presented in this panel will tackle these questions from an interdisciplinary point of view, confronting analitical tools from political science, history and political-economy.