Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a United States Department of Energy national laboratory specializing in high-energy particle physics. Since 2007, Fermilab has been operated by the Fermi Research Alliance, a joint venture of the University of Chicago, Illinois Institute of Technology and the Universities Research Association (URA). Fermilab is a part of the Illinois Technology and Research Corridor.

Fermilab's Tevatron was a landmark particle accelerator; at 3.9 miles (6.3 km) in circumference, it was the world's second-largest energy particle accelerator (after CERN's Lare Hadron Collider which is 27 km in circumference), until it was shut down in 2011. In 1995, the discovery of the top quark was announced by researchers who used the Tevatron's CDF and DØ detectors.