On September 29, 1954, twelve European states signed the convention establishing the European Organization for Nuclear Research, which took its acronym from the provisional body that had run the project since 1952. Its first site was at Meyrin, in a field on the Swiss side of the border with France, a few kilometres from Geneva. It came into force later.
The idea was not new. In December 1949 the Nobel laureate Isidor Rabi, then at UNESCO, proposed that Europe build a regional laboratory on the model of the American national laboratories, and the argument that carried it was partly scientific and partly about the future of Europe: a continent that had spent the war and its aftermath exporting its physicists would be giving them somewhere to work.
It was also cheap in the right way. A particle accelerator is not a weapon, which made it easy for governments to fund, and it is large and shared, which made it easy for them to fund together. The first machine, a 600 MeV synchro-cyclotron, started in 1957. The Proton Synchrotron, which accelerated protons to 28 GeV, started in 1959 and was for a while the highest-energy machine in the world.
What came out of it is the standard model and the web. CERN's Intersecting Storage Rings, which ran from 1971, were the first hadron collider. The Super Proton Synchrotron found the W and Z bosons in 1983, and Carlo Rubbia and Simon van der Meer got the Nobel Prize for it in 1984. The Large Electron-Positron Collider ran from 1989 to 2000 and measured the number of light neutrino families to be three.
Then the web. Tim Berners-Lee, a British software engineer at CERN, wrote a proposal in March 1989 for an information management system that would let physicists share documents across incompatible machines, and he wrote the first browser and server in 1990 and put the first website up in 1991. CERN put it into the public domain in April 1993.
The Large Hadron Collider, in a 27-kilometre tunnel on both sides of the border, started in September 2008 and found the Higgs boson in July 2012, which is the particle that gives mass to the others and the last piece of the standard model that had not been observed. CERN now has 23 member states, about 2,500 staff and about 17,000 visiting scientists, which makes it the largest particle physics laboratory in the world.