The CMS Electromagnetic Calorimeter: Construction, Commissioning and Calibration

The Compact Muon Solenoid (CMS) detector at the Large Hadron Colider (LHC) is ready for first collisions. The Electromagnetic Calorimeter (ECAL) of CMS, a high resolution detector comprised of nearly 76000 lead tungstate crystals, will play a crucial role in the coming physics searches undertaken by CMS. The design and performance of the CMS ECAL with test beams, cosmic rays, and first single beam data will be presented. In addition, the status of the calorimeter and plans for calibration with first collisions will be discussed.