La grande boucle souterraine : l'excavation du LEP fut la plus formidable entreprise de génie civil de l'histoire du CERN et le plus vaste chantier européen avant le tunnel sous la Manche.

Siting a 27-km long underground ring in the corridor between the Jura mountains and Lake Geneva was no easy matter. After several proposals, the decision was made to install the ring along the foot of the Jura range. However, owing to geological features the tunnel had to be built on a gradient of 1.4 %, sloping towards the Lake.