The existence of many individual camps and ghettos was previously known only on a fragmented, region-by-region basis. But the researchers, using data from some 400 contributors, have been documenting the entire scale for the first time, studying where they were located, how they were run, and what their purpose was.

The brutal experience of Henry Greenbaum, an 84-year-old Holocaust survivor who lives outside Washington, typifies the wide range of Nazi sites.

When Mr. Greenbaum, a volunteer at the Holocaust museum, tells visitors today about his wartime odyssey, listeners inevitably focus on his confinement of months at Auschwitz, the most notorious of all the camps.

But the images of the other camps where the Nazis imprisoned him are ingrained in his memory as deeply as the concentration camp number — A188991 — tattooed on his left forearm.

In an interview, he ticked off the locations in rapid fire, the details still vivid.

First came the Starachowice ghetto in his hometown in Poland, where the Germans herded his family and other local Jews in 1940, when he was just 12.

Next came a slave labor camp with six-foot-high fences outside the town, where he and a sister were moved while the rest of the family was sent to die at Treblinka. After his regular work shift at a factory, the Germans would force him and other prisoners to dig trenches that were used for dumping the bodies of victims. He was sent to Auschwitz, then removed to work at a chemical manufacturing plant in Poland known as Buna Monowitz, where he and some 50 other prisoners who had been held at the main camp at Auschwitz were taken to manufacture rubber and synthetic oil. And last was another slave labor camp at Flossenbürg, near the Czech border, where food was so scarce that the weight on his 5-foot-8-inch frame fell away to less than 100 pounds.

By the age of 17, Mr. Greenbaum had been enslaved in five camps in five years, and was on his way to a sixth, when American soldiers freed him in 1945. “Nobody even knows about these places,” Mr. Greenbaum said. “Everything should be documented. That’s very important. We try to tell the youngsters so that they know, and they’ll remember.”