South Magnetic Pole
Antarctica on 11 December 1957. The original stamp design of 1957, which included a map of Antarctica, was seen as an “aggressive geopolitical assertion of territory” by the Australians, due to the map clearly marking the territory’s boundaries.  This caused issues within Antarctica as a whole, as the “issuing of postmarks can only be performed by a sovereign state”. However, more than 23,000 letters were stamped with this postmark up until 1909, when several more stamps, such as the ‘Explorers at South Magnetic Pole’ and ‘Dog Sled and Team’ were released.