It was January 1945, and fires burned at Auschwitz-Birkenau. Not at the crematoria where, at the height of the Nazi concentration and extermination camp’s operations, an average of 6,000 Jews were gassed and cremated each day—those had been blown up at the command of SS officers preparing the camps’ evacuation. This time, the Nazis had set ablaze their prisoners’ looted possessions. The fires raged for days.

Once, the sprawling 40-camp complex now known as Auschwitz was characterized by grim record-keeping and brutal order. With chilling efficiency, the architects of the Holocaust orchestrated processes of deportation, detention, experimentation, enslavement and murder. Between 1940 and 1945, approximately 1.1 million Jews, Poles, Roma people, Soviet POWs and others were killed at the Auschwitz camps. Now, as Soviet troops marched westward through occupied Poland, the SS sought to dismantle their killing machine.

The Red Army’s arrival meant liberation, the camps’ end. But what came after the murders finally stopped?

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In the final days of the camp, the commanding SS officers “evacuated” 56,000 prisoners, most of them Jews. Leaving Auschwitz, however, did not mean the end of their ordeal. Instead, the SS ordered their charges into columns and marched them into the miserable winter. At first, the prisoners went on foot, monitored by officers who shot those who fell behind or tried to stay behind. Malnourished and inadequately clothed, the marchers were subject to random massacre. Eventually, they were shipped back toward Germany in open train cars. Up to 15,000 of the former camp inhabitants died on the death march.

“[The Nazis] wanted to continue to use those tens of thousands of prisoners for forced labor,” says Steven Luckert, senior program curator at the Levine Family Institute for Holocaust Education at the United States Holocaust Memorial Museum and former chief curator of the museum’s permanent collection. “Those prisoners got dispersed over all of the remaining camps.”

Back at Auschwitz, where by some estimates 9,000 prisoners remained, only a few SS guards maintained their watch. Most of the prisoners were too sick to move. “There was no food, no water, no medical care,” says Luckert. “The staff had all gone. [The prisoners] were just left behind to die.”

Among the last acts of the SS were to set fire to huge piles of camp documents, a last-ditch effort to hide the evidence. “They understood the enormity of the crimes they committed,” Luckert says.

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A surreal quiet fell on Auschwitz in late January, a period filled with confusion and suffering. Then, Soviet scouts stumbled into Auschwitz-Birkenau. The liberators had not intended to go toward the camp; though Soviet premier Joseph Stalin had heard about its existence in intelligence communications and conversations with other Allied leaders, Red Army commanders had no idea it existed. “It had no military or economic value from a military viewpoint,” retired Soviet general Vasily Petrenko, who in 1945 was a colonel who helped liberate the camp, told the AP years later.

The Soviets had liberated Majdanek, a Nazi concentration and extermination camp, in July 1944. There, they found a working camp that had been only partially destroyed during its hasty evacuation. It was the first Allied concentration camp liberation, and in the months to follow, the Allies would encounter many more camps as they squeezed the German army from the West and the East.

As Soviet scouts, then troops, arrived at the Auschwitz complex, bewildered prisoners greeted them with tears and embraces. Anna Polshchikova, a Russian prisoner, later recalled the gruff confusion of the first soldiers. “‘And what are you doing here?’ they inquired in an unfriendly manner. We were baffled and did not know what to say. We looked wretched and pathetic, so they relented and asked again, in a kinder tone. ‘And what is over there?’ they said, pointing northwards. ‘Also a concentration camp.’ ‘And beyond that?’ ‘Also a camp.’ ‘And beyond the camp?’ ‘Over there in, the forest, are the crematoria, and beyond the crematoria, we don’t know.’”

The first Soviet troops to arrive moved on toward other targets, but the Red Army soon took over the camps, establishing field hospitals on site. Polish Red Cross workers—volunteer doctors, nurses and paramedics who just months earlier had participated in the Warsaw Uprising—assisted in the recovery too. “The situation was desperate,” recalled Józef Bellert, the physician who organized the group. “We could barely administer the most urgent medical aid.”

As they got to work, they saw body parts strewn around ad hoc cremation pits used after the SS demolished Auschwitz-Birkenau’s crematoria; human excrement and ashes were everywhere. Survivors suffered from malnutrition, bedsores, frostbite, gangrene, typhus, tuberculosis and other ailments. And though the SS had attempted to destroy all evidence of mass murder, they had left massive storerooms filled with shoes, dishes, suitcases, and human hair. “It was chaos,” says Jonathan Huener, a Holocaust historian at the University of Vermont.

Once established, the Red Cross staff and local volunteers responded as best they could to the survivors’ needs, navigating a cacophony of different languages. They diagnosed patients, gave them identification documents and clothing, and sent over 7,000 letters to help the patients locate family and friends around the world. “Some of the sick did not realize that they were now free people,” recalled Tadeusz Kusiński, a Red Cross orderly. At least 500 of the 4,500 patients died, many from refeeding syndrome or a lack of sanitary facilities.

Those who could leave trickled out on their own or in small groups. “There were fears that the Germans would return, which for us would only mean death,” said Otto Klein, a Jewish adolescent who had survived medical experiments by infamous Nazi doctor Joseph Mengele along with his twin brother, Ferenc. Together with a group of 36 people, most of them twins, the Kleins headed toward Kraków, and eventually out of Poland, on foot. Not everyone chose to go: Others stayed in the camp to help former prisoners, including about 90 former prisoners who gave vital assistance to the Soviet and Red Cross hospitals.

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Auschwitz had been liberated, but the war still plodded on, shaping the massive camp complex. The camp was still a prison, this time for thousands of German POWs the Soviets forced to do labor that echoed that of the original Auschwitz prisoners. Along with some Polish people imprisoned for declaring ethnic German status during the war, the German POWs maintained the site, tore apart barracks and dismantled the nearby IG Farben synthetic rubber plant where tens of thousands of prisoners had been forced to work as slave laborers.

“Some of the barracks were simply dismantled by members of the local population who needed wood,” Huener says. Though the historian in him laments the deconstruction of so much of the camp, he says it was also “understandable in a period of tremendous deprivation and need.”

Over the months that followed the camps’ liberation, many former prisoners returned seeking family members and friends. And a small group of survivors came back to stay.

“The earliest stewards of the site were former prisoners,” explains Huener. In his book Auschwitz, Poland, and the Politics of Commemoration, 1945-1979, Huener tells the story of how the site went from operational death camp to memorial. Most of the cadre of men were Polish political prisoners, and none of them had experience with museums or historic preservation. But even during their imprisonments, they had decided Auschwitz should be preserved.

“We did not know if we would survive, but one did speak of a memorial site,” wrote Kazimierz Smoleń, an Auschwitz survivor who later became the memorial site’s director. “One just did not know what form it would take.”

Smoleń returned to Auschwitz after the war, drawn back to the camp by his desire to tell the world about the horrors committed there. He later described his return—and his 35-year tenure as the Auschwitz-Birkenau State Museum’s director—as “some type of sacrifice; an obligation for having survived.”

For Smolén and others determined to preserve Auschwitz, the site was both a massive graveyard and essential evidence of Nazi war crimes. But for others, it was a place to continue the plunder. Despite a protective guard, which included former prisoners, looters stole artifacts and searched through ash pits for gold tooth fillings and other valuables. “Gleaners, or as they were called at the time, ‘diggers,’ searched through the ashes of all the Nazi extermination camps in Poland [...] for many years after the war, looking for pieces of jewelry and dental gold overlooked by the Nazis,” write historians Jan Tomasz Gross and Irena Grudzinska Gross.

Huener says that there is no comprehensive answer to the question of how many of those early museum workers were Jews, or why they came back to Auschwitz. “Poland was inhospitable to Jews after the war, yet there were tens of thousands who did return to Poland, and tens of thousands who remained.” They did so despite a resurgence of anti-Semitism and violent incidents like the Kielce pogrom, in which 42 Jews were killed by massacred by townspeople who blamed Jews for a local kidnapping. Other Jews who survived Auschwitz fled Poland after being liberated, living in displaced persons camps, scattering into a worldwide diaspora, or emigrating to British Palestine.

The museum staff lived in former SS offices and did everything from groundskeeping to rudimentary preservation work to exhibit design. They staved off looters, acted as impromptu tour guides to the hundreds of thousands of visitors who streamed toward the camp, and tried their best to preserve everything that remained of the camp.

Despite the lack of modern preservation technology and questions about how best to present evidence of years of mass murder, the former prisoners who fought to preserve Auschwitz succeeded. The most notorious of the over 40,000 sites of systematic Nazi atrocities would be passed on to future generations. Other sites would fare differently, depending on the extent of their destruction by the Nazis and the deterioration of time.

When visitors in the 1940s and ’50s walked beneath Auschwitz I’s iconic “Arbeit Macht Frei” sign and into the camp, they were faced with buildings that looked much as they did during the Holocaust. The museum’s directive was to offer historical proof of the Germans’ crime—a mostly silent endeavor that left visitors in tears or simply speechless.

The exhibitions have changed over the years, but Auschwitz still inspires speechlessness. Last year, 2.3 million people visited the memorial, where 340 guides offer tours in 20 different languages. Now, Auschwitz has a state-of-the-art preservation laboratory, an extensive archive, and conducts education and outreach around the world. The end of Auschwitz was the beginning of a monumental task of preservation and commemoration that continues to this day.

But for Luckert, it’s important not to let the end overshadow the beginning. “Sometimes instead of focusing on the end, we need to look at how it got there,” he says. “What was it that led Nazi Germany to create such a symbol of inhumanity, a place of infamy? In a matter of a few short years, it transformed a sleepy Silesian town into the greatest site of mass killing the world has ever known.”

Seventy-five years after the Holocaust, he fears, it would be all too easy to get on the road to Auschwitz again.