
The resolution came after a special session was held earlier that year on 24 January 2005 during which the United Nations General Assembly marked the 60th anniversary of the liberation of the Nazi concentration camps and the end of the Holocaust.
27 January is the date, in 1945, when the largest Nazi death camp, Auschwitz-Birkenau, was liberated by Soviet troops. Prior to the 60/7 resolution, there had been national days of commemoration, such as Germany's Tag des Gedenkens an die Opfer des Nationalsozialismus (The Day of remembrance for the victims of National Socialism), established in a proclamation issued by Federal President Roman Herzog on 3 January 1996; and the Holocaust memorial day observed every 27 January since 2001 in the UK. The Holocaust Remembrance Day is also a national event in the United Kingdom and in Italy.
http://en.wikipedia.org/wiki/International_Holocaust_Remembrance_Day