Columbia served as a training center to teach and perfect new torture methods that would later be employed to run Germany's huge network of concentration camps around Europe.

"This was not just a place where people were terrorized and tortured, but a school of torture," Bernbeck added. "The people who had been commanders of Columbia later turned into commanders of other concentration camps - at Buchenwald, at Sachenhausen, at Majdanek, in Auschwitz, so once you had gone through concentration camp Columbia, apparently this was this perverse career step in order to stay in the SS and become a commander elsewhere."

The Nazis used the camp until 1936, when it was deemed too small. They sent here anyone whom Hitler considered an enemy: opposition politicians, Communists, union members, Jewish people, intellectuals, and homosexuals.

Bernbeck and Pollock said people who were not murdered here were kept for short stays of two or three weeks, and then released. Inmates were bussed every day from Columbia to the SS Headquarters (known today as the Topography of Terror museum, where they were interrogated.)

"The Nazis let people out purposefully after short periods of time so that word of how they were treated would spread." Bernbeck said. "It was a way to terrorize opposition groups, to shut them up."

The Columbia Concentration camp is also where the Germans perfected a system of classifying the people whom they enslaved.

"This is where they began to 'categorize' people. People from Poland had to wear a P; anyone from the Soviet Union wore 'O' for Ost, or east. There were Jewish forced laborers, then they were all deported from Berlin. There were French, Czech, Bulgarian forced laborers. People from Italy, Belgium, Netherlands -- from all over Europe, basically. We know that they lived in different barracks. But to what extent archeology can reveal the conditions -- which are to some extent known from documents -- we need to find out," Bernbeck explained.

***

An estimated 10,000 inmates passed through Columbia during its three-year lifespan. It was just one of around 3,000 forced laborer camps in Berlin alone. Bernbeck and Pollock maintain that Germans and others living in Berlin were well aware of these camps' existence. They point to rare stories of compassion -- borne out by evidence found during excavations -- of Berliners passing shoes and supplies to the inmates through Columbia's fences.

(Free University of Berlin)

In addition, underground groups distributed leaflets about the camp during the 1936 Olympics in Berlin.

"Obviously, we don't know who found and read the leaflets," Bernbeck said. "But when you think about it, such news spreads very quickly. People were fearful of being tortured in these places. Even people who were not in the opposition knew about these places too. That cannot be denied."