Sankt Georgen an der Gusen (also St. Georgen an der Gusen and St. Georgen/Gusen; lit.: "Saint George's Town on the Gusen River") is a small market town in Upper Austria, Austria, between the municipalities of Luftenberg and Langenstein. As of 2015 , the town had 3,779 inhabitants.
During World War II the town was selected to be the DEST-business administration center for exploiting slave labour in the quarries and later the industries of the Gusen concentration camp, a subcamp of the nearby Mauthausen concentration camp. In early 1944 the town became the site of "Gusen II", the most brutal sub-camp of Mauthausen. In roughly 40.000 m² of tunnels and caverns dug beneath St. Georgen for the Messerschmitt company a huge and most modern underground assembly plant for Messerschmitt Me 262 fuselages was operated until May 1945 under the code-name B8 Bergkristall - Esche II. In some trials of the Nuremberg Military Tribunal the relatively unknown term St. Georgen granite works was used to prevent the use of locations like Mauthausen or Gusen.