What did the Treaty of Rome do?
At a practical level, the Treaty established four institutions - a Commission, a Council of Ministers, a European Parliament and a European Court of Justice. These were to be staffed by officials, ministers, judges and parliamentarians from member states. They were in charge of creating closer co-operation on a range of economic and trade issues from agriculture to overseas aid, commerce to taxation. Another treaty was signed at the same time as the treaty establishing the European Community, which encouraged co-operation in the use of atomic energy, under an organisation called EURATOM, which was later absorbed into the structure of the European Community.
At a philosophical level, the treaty laid the foundation for 'ever closer union': establishing European government bodies, the freedom to move goods, capital and people, and the concept of cohesion - that member states should give economic support to each other to help all countries to grow at a similar rate.