Scientists are gathering in Geneva to bid farewell to the particle accelerator at the European Laboratory for Particle Physics (CERN), which has driven physics research for the past 11 years.
Scientists and ministers from some of CERN's 20 member states are joining this week's celebrations to mark the achievements of CERN's Large Electron Positron (LEP), which is due to be closed on November 2.
Many scientists have mixed feelings about the timing of the closure, which comes at crucial moment in the LEP's history.
The closure had been scheduled for the end of September. But the huge 27-kilometre accelerator was granted a one-month stay of execution after researchers detected what they hoped was evidence of the particle believed to be responsible for all the mass in the Universe.
The scientists at CERN wanted to follow up this chance to find the so-called "Higgs Boson" rather than leave the field open to American researchers while CERN installs a new accelerator, the Large Hadron Collider (LHC).
"We are very excited. We don't want to stop now," said Patrick Janot, who is responsible for the scientific co-ordination on the project.
The construction of the LHC will be completed in five years from now while an upgraded accelerator in the United States is due to start operating next year.
The decision to delay the closure of the LEP came following five measurements of particles, which scientists said could be the elusive Higgs Boson. The problem was that the measurements were not firm enough to constitute scientific evidence of the particle's existence.
The scientists then asked for a postponement of the closure to enable them to make new measurements.
The Higgs Boson is the last missing link in the so-called "standard model" of elementary particle physics.