The LHCb detector in the experimental hall located 90 meters below the surface. To the right is visible the transfer tunnel with the 10 meter diameter shaft linking the underground area to the surface hall above. On the backside the shielding wall (built of concrete blocks, 3.2 m thick) and in the corner the so-called chicane which allows persons passing between the accessible part of the hall behind the shielding wall and the experimental hall.

