Various other German industrial enterprises, such as Krupp and Siemens-Schuckert, built factories with their own subcamps. There were around 40 or 50 such camps, 28 of them near industrial plants, each camp holding hundreds or thousands of prisoners. Designated as Aussenlager (external camp), Nebenlager (extension or subcamp), or Arbeitslager (labor camp), camps were built at Blechhammer, Jawiszowice, Jaworzno, Lagisze, Mysłowice, Trzebinia, and centers as far afield as the Protectorate of Bohemia and Moravia in Czechoslovakia. Industries with satellite camps included coal mines, foundries and other metal works, and chemical plants. Prisoners were also made to work in forestry and farming. Budy, for example, was a farming subcamp where prisoners worked 12-hour days, often in the fields, but sometimes tending animals, cleaning ponds, digging ditches, and making compost. Human ashes from the crematorium were mixed with sod and manure to make the compost. Incidents of sabotage to decrease production took place in several subcamps, including Charlottengrube, Gleiwitz II, and Rajsko.
The Auschwitz Birkenau camp complex comprises 155 brick and wooden structures (57 in Auschwitz and 98 in Birkenau) and about 300 ruins. There are also ruins of gas chambers and crematoria in Birkenau, which were dynamited in January 1945. The overall length of fencing supported by concrete poles is more than 13 km. Individual structures of high historical significance, such as railway sidings and ramps, food stores and industrial buildings, are dispersed in the immediate setting of the property. These structures, along with traces in the landscape, remain poignant testimonies to this tragic history.
Heinrich Himmler's Schutzstaffel (SS) took full control of the police and the concentration camps throughout Germany in 1934–35. Himmler expanded the role of the camps to hold so-called "racially undesirable elements", such as Jews, Gypsies/Romanis/Sintis, Serbs, Poles, disabled people, and criminals. The number of people in the camps, which had fallen to 7,500, grew again to 21,000 by the start of World War II and peaked at 715,000 in January 1945.