The Broad Street cholera outbreak (or Golden Square outbreak) was a severe outbreak of cholera that occurred in 1854 near Broad Street (now Broadwick Street) in the Soho district of London, England. This outbreak, which killed 616 people, is best known for the physician John Snow's study of its causes and his hypothesis that contaminated water, not air, was the source of cholera.[1][2] This discovery came to influence public health and the construction of improved sanitation facilities beginning in the mid-19th century. Later, the term "focus of infection" would be used to describe sites, such as the Broad Street pump, in which conditions are good for transmission of an infection.