Engineers have begun a major upgrade of the Large Hadron Collider (LHC).
Their work should double the energy of what's already the most powerful particle accelerator in the world.
BBC News is the first to be allowed to see inside the LHC - on the French-Swiss border - to watch the work being carried out.
Scientists believe the upgrade will enable them to discover new particles which will lead to a more complete theory of how the Universe works.
A project leader with the LHC's Atlas experiment, Dr Pippa Wells, told BBC News that there was much more to come from the LHC.
"The past two years have been the most exciting in my time as a particle physicist. People are absolutely fired up. They've made one new discovery (the Higgs) and they want to make more discoveries with the new high energies that the upgrade will give us. We could find a new realm of particle physics."
I was taken by the technical coordinator for the upgrade project, Katy Foraz, and Cern's UK communications manager Stephanie Hills, to one of the many access points to the LHC's underground tunnels.
We entered a lift shaft with two buttons marked zero and minus 1. Katy hit minus 1 and we made our way 100m below the surface.
As we exited the lift, we walked to a large heavy green door that we strained to open.
As we went through, it was like entering Aladdin's cave.
No jewels or gold - but one of the largest and most complex machines ever built. A bright blue superconducting beamline stretches into the distance - around it are gleaming precision instruments to make the line one of the coldest places in the Universe.
In front of me, engineers were replacing some of the first connectors. In all, 10,000 will need to be changed. Eight hundred people are involved in this project, which will cost £70m.
The tasks also include testing and replacing some of the LHC's main dipole and quadrupole magnets, which are used to bend the paths of the particles and keep them tightly bunched; conducting tests to detect any irregularities in the magnets or imperfections in the electrical insulation; and a range of other work to improve the machine.
The LHC is known for its cutting-edge science. But as we walked to this scientific wonderland, Katy told me that people often forget that the particle accelerator is also on the cutting edge of engineering. After all, creating the conditions of the beginning of the Universe is no easy feat.
"We are always at the limit of what we know in terms of the technology. It is very exciting: as the coordinator. I have access to all the technologies and they really are at their limit in terms of superconductivity cryogenics. It is very exciting for an engineer to be close to all these new technologies," she said.
Katy and her team of engineers are calling the work an "upgrade". But critics say it's a "repair".
As we walked passed a team replacing a damaged connector, Cern's Stephanie Hills was quick to respond to the charge that this expensive refit is putting right a mistake that should not have been made in the first place.
more here: http://www.bbc.co.uk/news/science-environment-21941666