There is still a pump in the Golden Square neighborhood on what was once called Broad Street. It does not work, for it is merely a replica of the original, and like the original its handle is missing. It serves as a curiously simple monument to the events that took place over one hundred years ago, when the real pump supplied water to the Broad Street residents. In 1854, hundreds of these hapless locals dropped dead within days of each other as Soho experienced one of the most brutal outbreaks of cholera that London has ever seen. Not even the most eminent physicians could say what caused the disease, or why it came and went as it did. John Snow's solution to the cholera crisis broke the medical conventions of his era, slowed the progress of a virulent intercontinental disease, and forever changed the way society confronts public health problems. This article describes the life and legacy of John Snow whose contribution to history was the water-borne theory of cholera. (Contains 33 notes.)