In this photo taken in January 1945, survivors stand behind the gates of the camp at Auschwitz, as they watch the arrival of Soviet troops.

Soviet Red Army soldiers stand with liberated prisoners of the Auschwitz Concentration Camp in this 1945 photo.

A 15-year-old Russian boy, Ivan Dudnik, is rescued. The teen was brought to Auschwitz from his home in the Orel region by the Nazis.

An aerial reconnaissance photograph shows Auschwitz II (Birkenau Extermination Camp) on December 21, 1944.

Hungarian Jews arrive in Auschwitz-Birkenau, in German-occupied Poland in June 1944. Between May 2 and July 9, more than 425,000 Hungarian Jews were deported to Auschwitz.

Men selected for forced labor from amongst Hungarian Jews in Auschwitz-Birkenau, in German-occupied Poland, June 1944.

This photo of Auschwitz survivors was taken by a Soviet photographer in February 1945 during the making of a film about the liberation of the camp.

Child survivors of Auschwitz show their tattooed arms in a photo as part of the film about the camp’s liberation. Soviet filmmakers dressed the children in clothing from adult prisoners.

Two children in the Auschwitz medical station after the camp’s liberation. The Soviet army entered Auschwitz on January 27, 1945, and released more than 7,000 prisoners, most of whom were ill or dying.

This hospital card, produced by Soviet staff after the camp's liberation, describes the patient labeled No. 16557: 'Bekrie, Eli, 18 years, from Paris. Alimentary dystrophy, third degree.'

This medical card shows 14-year-old Hungarian boy, Stephen Bleier. The card diagnoses Bleier with alimentary dystrophy, second degree.

A Soviet army surgeon examines an Auschwitz survivor, Vienna engineer Rudolf Scherm.

Seven tons of hair, shown here in a 1945 photo, were found in the camp’s depots. Also recovered: more than 12,000 pots and pans brought by victims who believed they'd eventually be resettled.

Soviet soldiers inspect a pile of clothing items left behind at the camp on January 28, 1945.

Civilians and soldiers recovering corpses from the common graves of the Auschwitz-Birkenau concentration camp in February 1945. Of the 1.3 million people sent to the camp, more than 1.1 million were killed.