The story
The Gesellschaft für Erdkunde zu Berlin was founded in 1828 by some of the foremost geographers of its time, including the main founder Carl Ritter and founding member Alexander von Humboldt. It is the second oldest geographical society.
The Gustav Nachtigal Medal (Gustav-Nachtigal-Medaille), named after German surgeon explorer Gustav Nachtigal, was awarded from 1896 until the 1990s.
From Wikipedia’s article on Gesellschaft für Erdkunde zu Berlin, shared under CC BY-SA 4.0.5