This website features a GIS based "historical map with sites of Victorian London during the time of Dr. John Snow (1813-58), the prominent epidemiologist and anesthesiologist. [...] The graphics and programming for the GIS were done by Ralph R. Frerichs [...] The GIS has 712 cells (711 quarter-mile squares and 1 title square) which serve as links for additional historical information. The map continues to evolve over time with new locations and descriptions at the cell level, to be named when completed in the John Snow index and the London index."