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).
Treaty of Rome full name of which was the Treaty establishing the European Economic Community has been amended by successive treaties significantly changing its content. The 1992 Treaty of Maastricht established the European Union, the EEC becoming one of its three pillars, the European Community. Hence, the treaty was renamed the Treaty establishing the European Community (TEC). When the Treaty of Lisbon came into force in 2009, the pillar system was abandoned; hence, the EC ceased to exist as a legal entity separate from the EU. This led to the treaty being amended and renamed as the Treaty on the Functioning of the