The LHC makes maximum use of the LEP tunnel and CERN's existing
The LHC will be housed in the LEP tunnel (27 km in circumference
and 100 metres underground) which sits astride the Franco-Swiss
border close to Geneva.
The two beams of protons or heavy ions go in opposite directions
inside two ultra-high vacuum tubes which cross at four places.
It is at these intersection points that the detectors of the experiments,
ATLAS, ALICE CMS and LHCb will observe collisions.