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 over occupied Poland, shows Auschwitz II (Birkenau Extermination Camp) on December 21, 1944. It is one of a series of aerial photographs taken by Allied reconnaissance units under the command of the 15th U.S. Army Air Force during missions dating between April 4, 1944 and January 14, 1945.

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 pose 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 remaining prisoners, most of whom were ill and dying.

This is a card taken from hospital files produced by Soviet staff after the liberation of the camp. The information about the patient, labeled No. 16557, reads, “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 at the camp were some 3,800 suitcases; more than 88 pounds of eyeglasses; 379 striped uniforms; 246 prayer shawls, and more than 12,000 pots and pans brought to the camp by victims who believed they would eventually be resettled.

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

Civilians and soldiers recover corpses from the common graves of the Auschwitz-Birkenau concentration camp in this February 1945 photo. Some 1.3 million people were sent to the camp, according to the Holocaust Memorial Museum, and more than 1.1 million were killed.