The COVID-19 pandemic is revealing the many ways in which infectious disease control is a spatialized enterprise. Stay-at-home orders, travel bans and travel corridors, restrictions on visiting patients in hospitals, and many more regulations, speak to the power of space and place in conditioning the transmission of infectious diseases and the human experiences of them. Such spatializations have an extremely long history but were codified and formalized in the later nineteenth century as knowledge of bacteria, incubation periods, and asymptomatic carriers became more sophisticated. Two developments reflected this in Great Britain. First, the new use of the term 'contact' as a noun and the naming of 'contacts' as a specific population group. Second, the emergence of the 'reception house', a building for people living in overcrowded dwellings who had been exposed to people with infectious diseases but who were not yet showing signs of disease. Drawing on recent scholarship at the boundary of medical history, architectural history and the histories of biopolitics, this paper uses public health reports, architectural plans, and newspapers to reveal the multiple ambiguities of these spaces, where the uncertainties of bacteriological science, the demands of the capitalist labour system, and the rationales of liberal governance coalesced.