Even during the planning stages of the Mauthausen concentration camp, the SS acquired granite quarries in Gusen, a village located just a few kilometers away. From December 1939, prisoners from Mauthausen were forced to build a camp there. In April 1940, the first prisoners were permanently housed in the Gusen concentration camp and, until 1943, were primarily deployed for forced labor in the quarrying industry. In 1941, the SS company Deutsche Erd- und Steinwerke (German Earth and Stone Works) began expanding the existing quarry operations at the Gusen concentration camp with the construction of a gravel production plant, at the time the largest in Europe. From 1943 onward, up to 150 tons of granite per hour from the Gusen quarries were crushed here, loaded onto railcars via a direct rail connection, and transported via the connecting line to the Reichsbahn (German State Railway). The construction work had to be carried out by prisoners of the Gusen concentration camp. Many of them died during the construction and operation of this plant.

The stone crusher is a site of Nazi history, which, as a structural relic, facilitates engagement with the history of the site and the Nazi crimes committed there. As part of the EU campaign Twin it! – 3D for Europe’s Culture, several models were created for Europeana. The project was made possible by funding from the Federal Ministry for Housing, Arts, Culture, Media and Sport. Implementation was carried out in cooperation with Kulturgut Digital, EKG Baukultur ZT, the Austrian Federal Real Estate Agency (Burghauptmannschaft Österreich), and the Mauthausen Memorial.

The starting point for all models is the highly precise point cloud of the 3D laser scan, which serves as the basis for the planned restoration work. It forms the basis for planning documents as well as for static analyses and investigations of material properties. Using photogrammetry and the 3D Gaussian splatting technique, a highly detailed digital model was created. This enables a photorealistic 3D representation of the gravel crusher from various perspectives. This allows for the precise analysis of surface structures, textures, and the effects of weathering and changes. The model serves the long-term documentation, research, and digital accessibility of this historical site.

Developing a historical functional model of the gravel crusher presented a particular challenge. The goal was to reconstruct missing components and machinery and to make the plant's operation in the 1940s comprehensible. This was based on the intensive evaluation of building survey reports, photographs, and archival materials with the support of the Krupp Historical Archive and the Vienna Museum of Technology. Since only limited reliable information has survived, the model is intended as a reconstruction hypothesis and aims to stimulate further research and exchange with academics and citizen scientists.