Mauthausen Concentration Camp (known from the summer of 1940 as Mauthausen-Gusen Concentration Camp) grew to become a large group of Nazi concentration camps that was built around the villages of Mauthausen and Gusen in Upper Austria, roughly 20 kilometres (12 mi) east of the city of Linz.
Initially a single camp at Mauthausen, it expanded over time and by the summer of 1940, the Mauthausen-Gusen had become one of the largest labour camp complexes in German-controlled Europe.
In January 1945, the camps, directed from the central office in Mauthausen, contained roughly 85,000 inmates. The death toll remains unknown, although most sources place it between 122,766 and 320,000 for the entire complex. The camps formed one of the first massive concentration camp complexes in Nazi Germany, and were the last ones to be liberated by the Allies. Unlike many other concentration camps, intended for all categories of prisoners, Mauthausen was mostly used for extermination through labour of the intelligentsia, who were educated people and members of the higher social classes in countries subjugated by the Nazi regime during World War II.
Mauthausen was liberated by American troops in May 1945. It was declared a national memorial site in 1949 and a museum opened in 1975.