The European Organisation for Nuclear Research (CERN) was founded in 1954 by a group of men seeking to explore the fundamental building blocks of our Universe. Since then, they and a host of international scholars have succeeded, exemplified by the discovery of the Higgs Boson in 2012 and numerous Nobel Prize awards. But running parallel to the 'great men' of high-energy physics, is the untold story of the women of CERN. The organisation is an elite institution, and can thus provide insight into why numbers of women remain low in all facets of its work (except professional administrative). This viewpoint explores the role of women at CERN, both scientists and non-scientists, drawing on archival research from the organisation's collection in Geneva and interviews, providing an analysis of why gender diversity is still one of the puzzles left for this elite space to solve.