From today's Independent newspaper
"London Underground is in talks with the European Organisation for Nuclear Research (Cern) about the possibility of using the 23km tunnel of the Circle Line to house a new type of particle accelerator similar to the Large Hadron Collider in Geneva.
...Although there are still considerable technical problems to overcome, such as a geo-magnetic "kink" in the circuitry at Edgware Road station, Cern is quietly confident that it will be able to convince London Underground of the merits of the scheme, which should result in the first air-conditioned underground line as a spin-off of installing supercooled magnets below ground.........."