The remodelling and enlargement of the London Hospital between 1884 and 1919 by the architect Rowland Plumbe modernized one of the largest general hospitals in Britain. The work almost entirely concealed the mid eighteenth-century core of the hospital and extended its footprint beyond its immediate grounds, creating a sprawling medical complex on the south side of Whitechapel Road. The transformative effect of Plumbe's work was centred on procuring sanitary and functional interiors. During an association that spanned thirty-five years, Plumbe designed well-ventilated wards, bright operating theatres, and highly specialized departments. Nurses' homes were planned to preserve discipline and respectability, forming a cluster of tall dormitory blocks connected by covered bridges. This essay, based on research for the Survey of London, considers the medical expertise, organizational principles and social values that shaped a complicated building programme to upgrade an historic infirmary into a hygienic, well-supervised and efficient hospital complex.