Golden Jubilee photos: The Big Dig

The excavation of the LEP tunnel was the most formidable civil-engineering venture in the history of CERN and Europe's largest civil-engineering project prior to the Channel Tunnel.
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.
Three tunnel-boring machines started excavating the tunnel in February 1985. One year into the project there was a major geological accident when substantial quantities of high-pressure water, sand and mud burst into the tunnel, halting operations for several months. Once the problem was overcome, work resumed and the ring was completed on 8 February 1988.
Despite its size, the tunnel accounted for less than half the 1.4 million cubic metres of spoil excavated from the site. The LEP facility also included a number of access shafts as well as four huge experimental caverns and numerous galleries and service tunnels.