The ceremony was attended by some 10,000 people from nearly 40 countries. The Croatian delegation was led by Croatian Parliament Seputy Speaker Djurdja Adlesic.
The Mauthausen concentration camp was established shortly after Germany annexed Austria in March 1938. It was built near an abandoned stone quarry, along the Danube River, about three miles from the town of Mauthausen in Upper Austria, some 20 kilometres southeast of Linz.
An estimated 199,400 prisoners passed through Mauthausen between 1938 and May 1945. Of these about 119,000 prisoners are believed to have died in Mauthausen and its subcamps. A third of them were Jewish.
On May 5 1945, units of the American 11th Armor Division liberated the main Mauthausen camp. 15,000 bodies were buried in mass graves. Due to diseases and starvation, 3.000 prisoners died in the weeks that followed after the liberation.