The ATLAS experiment is being constructed by 1800 collaborators in 150 institutes around the world. It will study proton-proton interactions at the Large Hadron Collider (LHC) at the European Laboratory for Particle Physics CERN . The detector is due to begin operation in the year 2007. The primary purpose of the detector will be studies of the origin of mass at the electroweak scale, therefore the detector has been designed for sensitivity to the largest possible Higgs mass range. The detector will also be used for studies of top quark decays and supersymmetry searches.