This cache is one in an ongoing series highlighting important figures in the history of the academic discipline of geography. If you complete this series, you might be ready to pass your qualifiying exams for a PhD in Geography!
Walter Christaller (1893-1969) was a German geographer best known for the development of "central place theory." Central place theory examines how amenities such as stores and government offices will be arranged geographically to serve the population. Christaller showed that on a flat plain, with population distributed evenly across it, these amenities would be located at "central places" who each served a hexagonal area around them. The territories of central places would then combine into higher-order hexagonal territories for higher-order amenities.
During World War II, Christaller was hired by the SS to plan out the German occupation of eastern Europe according to his central place theory. After the war, he joined the communist party, as socialist governments seemed more likely to use his theories for rational planning of geography.