For my dissertation, I explain how I have contributed to several areas of the ATLAS experiment for both hardware and analysis. On the detector side, this paper will examine my contributions to the New Small Wheel, part of the muon system installed for Run 3, and the ongoing development of the Inner Tracker, a silicon pixel upgrade for the High Luminosity LHC. My analysis work on exotic Higgs decays, probing physics beyond the Standard Model, will also be covered in a description of the $H rightarrow aa rightarrow bbtautau$ analysis.