The purpose of this final paper is to understand the history and institutional framework of the European Union through the founding treaties, but also on the other treaties on which the Union is based. The Treaty of Lisbon as the cornerstone of all the other treaties, and the treaty that brings together all the existing treaties has been placed at the spotlight of this paper. The changes brought by the Lisbon Treaty to the functioning of the European Union are definitely immeasurable if we compare them with the changes in the previous treaties. Furthermore, the paper is turned to the past, the present and the future of the European Union, Croatia as a candidate and ultimately member of the European Union, and further consequences of EU policy towards member states. Britain's exit is one of the consequences of slow transformation, but also the degradation of the European Union, which has been dealt with in this final paper.