  The ATLAS experiment at the Large Hadron Collider (LHC) at CERN is currently
waiting to record the first collision data in spring 2009. Its muon
spectrometer is designed to achieve a momentum resolution of 10% pT(mu) = 1
TeV/c. The spectrometer consists of a system of three superconducting air-core
toroid magnets and is instrumented with three layers of Monitored Drift Tube
chambers (Cathode Strip Chambers in the extreme forward region) as precision
detectors. Resistive Plate Chambers in the barrel and Thin Gap Chambers in the
endcap regions provide a fast trigger system.
  The spectrometer passed important milestones in the last year. The most
notable milestone was the installation of the inner layer of endcap muon
chambers, which constituted the last big piece of the ATLAS detector to be
lowered in the ATLAS cavern. In addition, during the last two years most of the
muon detectors were commissioned with cosmic rays while being assembled in the
underground experimental cavern. We will report on our experience with the
precision and trigger chambers, the optical spectrometer alignment system, the
level-1 trigger, and the ATLAS data acquisition system. Results of the global
performance of the muon system from data with magnetic field will also be
presented.
