Treaty of Rome
The Treaty of Rome, officially the Treaty establishing the European Economic Community (or EEC Treaty in short) brought about the creation of the European Economic Community (EEC), the best-known of the European Communities (EC). It was signed on 25 March 1957 by Belgium, France, Italy, Luxembourg, the Netherlands and West Germany and came into force on 1 January 1958. Under the name Treaty on the Functioning of the European Union, it remains one of the two most important treaties in the modern-day European Union (EU).
— Wikipedia
The signature page of the Treaty.