The Commissioning and Start-up of the CMS Experiment by Nicolo Cartiglia, INFN, Turin, Italy Abstract: In this talk I will review the design, construction, assembly and preparations of the Compact Muon Solenoid (CMS) experiment for LHC: after almost 20 years of preparation CMS is ready to start data taking. The main design features of the detector will be analyzed and the commissioning and preparation for beam wth the ups and downs of the start-up will be discussed.