A Particle accelerator is a large machine that uses electric fields to accelerate particles that have electrical charges. Two different types are linear and circular. Linear machines have functions in areas of medicine, while circular accelerators are the types that are used to search for subatomic particles.
The Large Hadron Collider (LHC) is a particle accelerator, with a circumference of 27km, located at the CERN facility located on the border of France and Switzerland. Built over 15 years at a cost of $9 billion, it is the largest and most ambitious piece of machinery ever conceived and built by man.