The Large Hadron Collider (LHC) is an international, collaborative project to probe the nature of matter. It has been under construction for the better part of a decade, and a major component, the compact muon solenoid (CMS) is now functional. The CMS produces a magnetic field 100,000 times stronger than the Earth's. It is the largest solenoid ever built. Once the LHC is online, the experiments conducted there are expected to help answer questions about matter, and in particular, the nature of dark matter.
Personally, when so much of world news can be disheartening, I'm always amazed by projects like this that bring nations together (the Human Genome Project is another example). Thirty-six nations are participating, and the experiments will take place at the LHC site at CERN, in Switzerland and France (it's a big place!)