How long did it take to build the LHC?

Question: How long did it take to build the LHC?
- Keywords:
  building,
  duration,
  LHC
Asked by kieranc on 13 Dec 2023.
- Joel Goldstein answered on 13 Dec 2023:
  
  The LHC project itself officially started when it was approved by CERN in 1994, and the main experiments were approved by 1996. The first collisions took place in 2009.
  
  However, a lot of design work and studies had already been done in order to get the project approved, and the tunnel the LHC sits in was actually built for the previous collider at CERN (LEP): that took about 5 years to complete, starting in 1983.
  
  So construction and installation of the LHC and experiments officially took about 15 years, but you could argue it was really more like 20 (including the tunnel) or even 25 (including the preparatory work).