The 27km circular tunnel has taken 13 years to complete 80m below the Swiss-French Alps. Tomorrow it will finally have a purpose when the European Organisation for Nuclear Research opens the centre.
The LHC is the world's most powerful particle accelerator, producing beams seven times more energetic than any previous machine.
It will use huge magnets to accelerate subatomic particles around the 27km tunnels to close to the speed of light, and then smash them together to see what happens.
Researchers hope this will re-create conditions similar to those at the beginning of the universe, and unmask the "God particle" (also known as the Higgs boson) – the source of all matter.
British civil engineering firms played a huge part in designing and building the series of 30m high, 200m long caverns to house the magnetic detectors to record the particle collisions.
They were also involved with building the tunnels along which the particle beams travel and deep access shafts through which equipment was lowered.
They included: Knight Piesold (now Scott Wilson), Gibb (now Jacobs), Howard Humphreys (now KBR Tunnels), Taylor Woodrow and Amec.
"In achieving this historic and massive scientific event NCE readers should be aware of the significant UK design and construction input," said International Tunnelling Association president Martin Knights, who worked on the project himself.