Soho
John Snow mapped the addresses of the sick, and noted that they were mostly people whose nearest access to water was the Broad Street pump.  He persuaded the authorities to remove the handle of the pump, thus preventing any more of the infected water from being collected.  The spring below the pump was later found to have been contaminated with sewage.  This is an early example of epidemiology, public health medicine and the application of science–the germ theory of disease.