To test for the presence of the Higgs-Boson, scientists constructed the largest human-made machine called the Large Hadron Collider (LHC) near Geneva, close to the Franco-Swiss border. The LHC is a ring-shaped tunnel that runs 27 kilometers long (equivalent to the Circle Line from London's Underground) and lies 100 meters underground.
Through this tunnel, subatomic particles are fired in opposite directions with the help of the aforementioned magnets with speeds approaching the speed of light. Once a critical speed is reached, the particles are put on a collision course where detectors monitor and record the collisions. There are literally millions upon millions of collisions and sub-collisions! - and the resultant particle debris give in hope of detecting the Higgs-Boson.