Adam Hart-Davis follows the construction of one of the most complex experiments ever attempted. The new Large Hadron Collider atom smasher at CERN has 6,000 superconducting magnets to steer the proton beams travelling at the speed of light around its 27-kilometre particle race track. Electronic detectors the size of churches observe new matter created inside the machine, and a hundred thousand computers around the world are standing by to analyse all the data.