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).
High Authority of the European Coal and Steel Community reached. Future executives, the Commissions of the EEC and Euratom, would eventually be based in Brussels. High Authority of the European Coal and Steel Community The High Authority was the executive branch of the former European Coal and Steel Community (ECSC). It was created in 1951 and disbanded in 1967 when it was merged into the European Commission. The High Authority was at the core of the idea of the ECSC. It was to be an independent, supranational executive checked by a Common Assembly. There were concerns about this power, leading to a Council (of governments) and Parliament (of MPs)