Since its inception, the European Union (EU) has pushed its borders by pursuing a European unification process. Within this framework, Article 49 of the Treaty on the European Union enshrines that any State which is “European” can be eligible for membership of the EU. In other words, the State must belong to “Europe”, a fundamental condition that indirectly but legally sets a limit to EU expansion. Nonetheless, the concepts of “Europe” and “Europeanness” have never been officially defined by the EU institutions, which casts doubt on the maximum external borders that the EU could take on. Failing an official definition, the EU institutions have still provided both implicit and explicit interpretations of the term “European” in their institutional discourse, especially in the course of enlargements and treaty-making processes. Building on a content analysis of primary sources mainly kept in the Historical Archives of the EU at the European University Institute in Florence, the article investigates these interpretations and how they resulted in both the bordering and the ordering of Europe through normative conditions and politico-cultural constructs, as well as shaped an institutional conceptualization of “Europe(-anness)”.