CERN exists primarily to provide them with the necessary tools. These are accelerators, which accelerate particles to almost the speed of light and detectors to make the particles visible.
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Part is in Switzerland, part in France across the border. CERN is not a Swiss institute, but an international organization. We are very close to Geneva's intercontinental airport.
This link provides a detailed view of CERN: http://cern.ch/area-map/AreaMap.html
And yes, this is the same CERN as in Angels and Demons.