The Compact Muon Solenoid at the LHC At the LHC two large general purpose experiments are being installed. One is the ATLAS experiment. The other is known as the Compact Muon Solenoid (or CMS). For three years I enjoyed an EU research grant at INFN Pisa and had the pleasure to work on the preparation of this great experiment (and principal competitor to ATLAS). One of the things I enjoyed most was the final validation (commissioning) of assembled layers of the CMS tracker. We have written up the most important findings in this note . It is currently being refereed, so please do not circulate this draft.