Fermilab is home to the Tevatron, the world's second-highest-energy proton-antiproton collider.

Four miles in circumference, the Tevatron is housed in a tunnel about 30 feet below the big ring you see in this aerial view of the laboratory. We use a series of accelerators to send particles racing around the Tevatron at 99.9999 percent of the speed of light in a vacuum. The particles complete the four-mile course nearly 50 thousand times a second.