Brussels and the European Union a provisional seat, though with the Common Assembly in Strasbourg as that was the only city with a large enough hemicycle (the one used by the Council of Europe). This agreement was temporary, and plans were set to relocate the institutions to Saarbrücken which would serve as a "European District", but this did not occur. The 1957 Treaties of Rome established two new communities, the European Economic Community (EEC) and the European Atomic Energy Community (Euratom). These shared the Assembly and Court of the ECSC but created two new sets of Councils and Commissions (equivalent to the ECSC's High Authority).
European Economic Community the European Union, though limited in some areas due to the pillar structure. Despite this, Parliament in particular has gained more power over legislation and security of the Commission. The Court was the highest authority in the law, settling legal disputes in the Community, while the Auditors had no power but to investigate. The EEC inherited some of the Institutions of the ECSC in that the Common Assembly and Court of Justice of the ECSC had their authority extended to the EEC and Euratom in the same role. However the EEC, and Euratom, had different executive bodies to the ECSC.