Drawing on both archival research and recent scholarship, this article examines how medical thinking and a scientific understanding of the atmosphere shaped the design of the Queen Alexandra Sanatorium in Davos, Switzerland, designed by Pfleghard & Haefeli from 1905 onward. While the sanatorium is noteworthy in terms of both its construction and its reception in the historiography of modern architecture, this study reassesses the rationale behind the design. Proposing an environmental cure, the institution did away with the idea of architecture as a protective wrapper, and instead presented the atmosphere itself as the primary realm for human habitation. This study thus situates the sanatorium in the atmosphere rather than in the landscape, even though the building appeared to grow from the ground. Conceived with the atmosphere as its proxy envelope, the sanatorium was designed to expose its patients to the celebrated air of Davos, praised for its purity and perfect stillness.