The Mace Head Atmospheric Research Station is located near Carna, Co. Galway on the west coast of Ireland, and is operated by personnel from the School of Physics of the University in Galway. It is an internationally recognised site and this unique facility on the western seaboard of Europe observes clean marine air from the North Atlantic for more than 50% of the time. It is a baseline station, since 1994, for the Global Atmosphere Watch of the WMO, as well as a designated European Monitoring and Evaluation Programme (EMEP) supersite. Over the past twenty years and more, considerable expansion of facilities has taken place at the station, which has hosted several important international research programmes, field campaigns and workshops. The suite of instrumentation deployed at Mace Head has recently been expanded to include some major new acquisitions for atmospheric remote sensing.