A People's Calendar (aPC) is an open-source project that seeks to promote the worldwide history of working class movements and liberation struggles in the form of a searchable "On This Day" style calendar.
On this day in 1945, the Soviet Red Army liberated Auschwitz concentration camp in Nazi-occupied Poland, the largest such complex during the Holocaust. In 2005, the United Nations named today as International Holocaust Remembrance Day.
Image: Prisoners being led out of the Auschwitz gates, possibly a re-enactment taken a few weeks after January 27th. The motto "Arbeit macht frei" (English: "Work sets you free") can be seen above the gate. [Wikipedia]