CERN is the European Organization for Nuclear Research, the world’s largest particle physics laboratory, situated on the border between France and Switzerland, just west of Geneva. It is also known for being the birthplace of the World Wide Web. The convention establishing it was signed on September 29, 1954. From the original 12 signatories of the CERN convention, membership has grown to the present 20 Member States.
Most of the activities at CERN are currently directed towards building a new collider, the Large Hadron Collider (LHC) and the experiments for it, due to start operation in 2007. This will use the 27 km circumference circular tunnel previously occupied by LEP which was closed down in November 2000, and the PS/SPS complex to pre-accelerate protons which will be injected into it. The tunnel is located 100 m underground, in the region between the Geneva airport and the nearby Jura mountains. Five experiments (CMS, ATLAS, LHCb, TOTEM and ALICE) are currently being built, and will be running on the collider; each of them will study particle collisions under a different point of view, and with different technologies. Construction for these experiments needed an extraordinary engineering effort. Just as an example, to lower the pieces for the CMS experiment into the underground cavern which will host it, a special crane will have to be rented from Belgium, which will be able to lift the almost 2000 tonnes of each piece. The first of the approximately 5,000 magnets necessary for construction was lowered down a special shaft at 1300 GMT on March 7, 2005.