Gran Sasso laboratory entrance. Time-exposure image of car light trails by the entrance to the physics laboratories at Gran Sasso in Abruzzo, Italy. In 2003, this tunnel system is the largest underground laboratory for particle astrophysics in the world. Experiments are conducted here to detect dark matter and neutrinos, elementary particles that travel across the universe. The laboratories are located 1400 metres underground, and are accessed from a 10 kilometre long road tunnel. The rock overlay shields the laboratories from cosmic rays.