ATLAS Muon Spectrometer

The muon spectrometer of the ATLAS experiment at the Large Hadron Collider (LHC) at CERN was designed to achieve a momentum resolution of better than 10% at 1 TeV. It consists of three superconducting air-core toroid magnets instrumented with three layers of precision drift chambers and dedicated fast trigger chambers. During the commissioning of the full ATLAS detector in the last year several 100 millions of events of cosmic ray data were recorded. We will report on the status and our experience with the muon precision tracking and trigger chambers, the level-1 trigger, and the spectrometer alignment. The global performance of the muon system will be discussed. The readiness of the ATLAS muon spectrometer for first collisions will be demonstrated.