The systematic murder of more than six million European Jews and millions of others by the Nazi regime was not confined to a single infamous location, but rather unfolded across a sprawling, meticulously engineered network of terror that included concentration camps, forced labor camps, and dedicated extermination centers. While Auschwitz-Birkenau has rightly become the symbol of this industrial-scale genocide, the full scope of the horror reveals a continent-wide machinery of death, where brutality was systematized, sadism was rewarded, and human life was rendered utterly expendable. The liberation of these camps by Allied forces unveiled not just physical remains, but the chilling evidence of a state whose primary purpose had become the annihilation of entire peoples.

The first camp established by the Nazis, Dachau, opened its gates on March 10, 1933, less than two months after Adolf Hitler assumed power. Located just north of Munich, the camp was built within the walls of an abandoned munitions factory, with the initial inmates themselves forced to construct the very buildings that would house their tormentors and, later, serve as a memorial to their suffering. The first prisoners were political opponents—thousands of Social Democrats, Communists, and other dissidents were swept into the camp within months.

In its first year, approximately 5,000 people were held, and many of the early victims were released under a sinister condition: they were forbidden, on pain of return, from ever speaking of the raw brutality they had witnessed and endured.

The first commandant of Dachau was Theodor Eicke, a longtime Nazi and a man of notorious sadism whose coarse behavior had made him an outcast even within the SS. Yet, this very cruelty made him the perfect choice for the role of camp commandant. Eicke was unforgiving and seemingly without mercy, and he urged his men to act with “inflexible harshness” toward all prisoners.

He was also the first to employ the infamous phrase “Arbeit macht frei” or “work sets you free,” which was emblazoned on the camp’s gate and would become the cynical motto for the entire concentration camp system. Eicke and his staff developed the administrative and disciplinary protocols that would govern nearly all camps the Nazis would subsequently build across Europe.

It is a critical distinction that places like Dachau were concentration and work camps, not extermination camps, yet hundreds of thousands of people still died or were killed within their fences. They were not merely prisons; they were instruments of terror and forced labor. It is estimated that at least 32,000 people died at Dachau itself, but tens of thousands more were transferred to Auschwitz after 1942, and a great many perished in the more than 150 Dachau subcamps scattered throughout Southern Germany and Austria.

Dachau was also the site of some of the most brutal and well-documented medical experiments carried out by the Nazis, including submerging victims in ice-cold water until they died, placing them in excruciating low-pressure chambers, and injecting them with various diseases and substances, all in the name of science, much of it conducted for the German air force, the Luftwaffe.

In the early years of the Nazi regime, most women prisoners were held in Germany’s civilian prisons, but as the flood of inmates increased and the camp system was perfected, dedicated camps for women were constructed. While there were numerous such camps, most of them subcamps of larger installations, two stood out for both their size and their cruelty: the women’s section at Auschwitz and the Ravensbrück Concentration Camp, located about 50 miles north of Berlin. Ravensbrück was also the primary training ground for the SS women’s auxiliary guards, known as Aufseherinnen.

Many of these women went on to command smaller subcamps, oversee the women’s camp at Auschwitz, and become some of the cruelest guards in Holocaust history, having earned their stripes at Ravensbrück through beatings, lashings, and a litany of other cruel punishments inflicted on female prisoners by other women.

Conditions at Ravensbrück were always abysmal, but by 1943, it had become a true horror show. Disease and hunger, combined with the sadism of the guards, made the camp infamous. By late winter 1945, the camp had become grossly overcrowded due to the lack of transport caused by the war and the evacuation of camps further east, such as Auschwitz.

Other concentration camps, including Bergen-Belsen and Buchenwald, were overrun by Western Allied forces at the end of the war before the prisoners within could be killed or marched away. These camps, in particular, shocked the world with their scenes of cruelty, filth, starvation, disease, and stacks of dead bodies. Much of the documentary footage of the camps after liberation comes from these two sites, providing the world with undeniable visual proof of the atrocities.

Among the most well-known Arbeitslager (work camps) were Mauthausen and Mittelbau-Dora. Mauthausen was officially a subcamp of the Dachau system, located halfway between Vienna and Salzburg, not far from Linz, Austria, where Hitler had grown up. Though officially part of the Dachau system, it essentially ran on its own.

Mauthausen was a work camp, but it was also a punishment camp; many of the men sent there were prisoners the Nazis particularly disliked or wanted to make an example of. The work at Mauthausen most often meant death, and the most infamous part of the camp was the quarry, where prisoners broke and hauled rocks for construction. Sometimes, the rocks served no purpose at all; they were simply carried until the prisoner collapsed and died.

This occurred on the “Stairway of Death,” where prisoners carrying blocks of stone on crude wooden frames on their backs were forced to climb a very steep 186 steps of uneven and wet granite.

During the war, the Stairway of Death claimed thousands of lives. Many of the prisoners were starving, sick, or suffering from wounds inflicted by guards or the work itself. Those who reached the top would often be sent back down to walk the stairs again and again.

The blocks of stone carried by victims would often fall, tumbling down the hill and through the rows of prisoners, killing some and injuring many more, who would later perish from their injuries. Other inmates who made it to the top might be taken to a nearby cliff, called the “Parachutist’s Wall” by the guards. At the cliff, inmates might be pushed off to their deaths below, or given a cruel choice: to earn life, perhaps only for hours or days, a victim had to push another inmate off the wall to his death.

A number of men chose to jump from the cliffs themselves, their last act of personal will, rather than push another prisoner or suffer through another back-breaking day. At times, guards would push large rocks off the cliffs or force inmates to do so, directly onto the men working below, often making a game of it and betting on whether a rock would hit or kill someone. Though Mauthausen was a work camp, at least 95,000 people died there.

Dora, or Mittelbau-Dora, was located in the southern Harz Mountains in central Germany and was originally part of the Buchenwald camp system. When it began in the summer of 1943, prisoners from Buchenwald were sent to build a large industrial complex in the deep forests and man-made caves and tunnels of the area. The central focus of the work at Mittelbau-Dora was the top-secret V-weapons program, which built the revolutionary V1 and V2 rockets, as well as lesser-known prototypes.

At its height in 1944, Dora held about 60,000 people, including men, women, and a number of children. Most of those brought to Dora never left; the information they held was too important. Until the U.

S. Army liberated the camp and its subcamps in April 1945, the only way out of Dora was to die. Twenty thousand people died at Dora, one-third of all those sent there.

While hundreds of thousands of victims died in the concentration and work camps, the sole or main purpose of those camps was not killing, though death was expected in most cases. There were only six dedicated extermination camps, and it was these camps that claimed the majority of lives taken by the Nazis during the Holocaust. In order of operation, they were Chełmno, Majdanek, Bełżec, Treblinka, Sobibór, and Auschwitz-Birkenau, all located in Poland.

Though most people simply call the extermination camp “Auschwitz,” the Auschwitz camp system included three main camps: Auschwitz I, Auschwitz II-Birkenau (sometimes known as just Birkenau), and Auschwitz III-Monowitz, an industrial complex to the east of the other two camps. It was at Auschwitz-Birkenau that the infamous gas chambers and crematoria were built.

Before and during the establishment of the extermination camps, over 1 million people, mostly Jews, were killed by the Nazi Einsatzgruppen, or special action groups, in mass shootings. Many of these killings were quite public; many people watched them happen, and some German soldiers took pictures despite orders against it. Not only did SS Chief Heinrich Himmler want to hide the killings as much as possible, but they also recognized that the killing of so many people was taking a psychological toll on his men, never mind the victims or witnesses.

In the fall of 1941, he ordered construction to begin on camps whose main function was killing. Though both Auschwitz and Majdanek had a number of work camps and subcamps around them, among the extermination camps, the most deadly in terms of the numbers of people killed in the shortest amount of time was Treblinka. Over 900,000 men, women, and children were killed at Treblinka, most of them soon after they arrived.

Treblinka was operational only until October 1943, when it was closed and those destined for it were sent to Birkenau.

At Bełżec, Chełmno, Treblinka, and Sobibór, carbon monoxide gas from truck or tank engines was used to kill. At Auschwitz and the smaller Majdanek camp, the infamous Zyklon B gas was used in specially made gas chambers, which at Majdanek were left relatively intact when the Germans fled in the summer of 1944. The sheer scale of the horror is almost incomprehensible.

Over 6 million European Jews and an approximate two to four million others—including Roma, Soviet prisoners of war, Polish intellectuals, disabled people, and political prisoners—were killed during the Holocaust. Many, if not most, of them were murdered in the camps. The liberation of these sites revealed not just the physical evidence of genocide, but the profound depths of human cruelty and the terrifying efficiency of a state dedicated to mass murder.