Millions across Europe, a majority of them European Jews, were brought to death camps for slaughter during the Nazis’ campaign in World War II. Those that weren’t immediately gassed, hung, shot or burned, were forced to labor for the Nazi forces from inside the electrified barbed-wire camp fences.

Auschwitz-Birkenau is the largest of the camps, including room for laborers as well as the facilities to wipe out thousands. Initially, two farm houses were modified and used as gassing chambers at Auschwitz-Birkenau, but later deemed insuffienct by the SS. The farm houses would not suffice due to the shear amount of people the SS planned to gas.

Over the course of just a few months in 1943, four large buildings were constructed, each containing a disrobing area, gassing chamber and crematorium. These facilities were in use until November of 1944.

Yet, some managed to escape the gas chambers and firing squads. A few made it past the beatings and the lack of health care. Some even managed to make it beyond the inadequacy of their clothing and the absence of food.

A few survived.

Tuesday marked the 70th anniversary of the liberation at Auschwitz-Birkenau concentration camp in Poland.

Roughly 300 survivors gathered at the entrance to the camp on Tuesday to commemorate the occasion. The occasion being the day Allied troops marched through the gates in 1945 during its advance on Berlin.

They wear their ID tattoos as badges of honor. Their weathered skin tells the story of true hardship, pain and suffering. They have not taken life for granted the way so many have in this day and age. These men and women have overcome some of the most horrifying conditions known to man.

They are still surviving.