The camp kitchen - one of the largest service buildings in Auschwitz, with state-of-the-art cooking facilities.
There were twelve of these throughout the camp.
The caloric content of the diet was carefully monitored by camp and Red Cross delegates. It only deteriorated in Auschwitz and other camps towards the end of the war when German railroads and the entire transport system collapsed under constant aerial attacks.
Air raid shelter door at Auschwitz
Hans Lamker and Hans Nowak have shown in detail how the SS installed modern (and highly) expensive microwave delousing facilities to protect the lives of inmates. 
Together with Michael Gärtner and Werner Rademacher, they are currently working on a comprehensive history of the Auschwitz camp, equipped with all means necessary to ensure the survival of tens of thousands of prisoners: hospitals, dentists, kitchens, laundries, butchers, as well as recreation facilities like sport fields and gardens.
Together with the fact that the overall costs of erecting this camp complex were on the order of magnitude of some five hundred million dollars, these facilities clearly contradict an intention by the German authorities to use this camp as an extermination center. There are cheaper ways of killing humans than to spend 500 dollars per capita. 
Compare it to the postwar American death camps along the river Rhein in Germany, where German POWs were held captured and died by the thousands between 1945 and 1947 due to lack of food, water, and medical care. All you need for an extermination camp is barbed wire and a few guards, just a few thousand dollars in materials.
2. W. Rademacher, M. Gärtner, "Berichte zum KL Auschwitz", VffG 4, no. 3-4 (2000)
Did the Inmates in Auschwitz know?
Traditional Holocaust historiasns claim in many of their arguments that in Auschwitz nobody knew what was going on 24 hours a day at the other side of the fence. That is the only way to explain many passages of what survivors tell about their experiences in the camp, mainly a common life in a work camp.
But...according to Eliezer Hauser, the brother of a Sonderkommando, the smell of burning bodies from the crematoria was constantly in the air.
When Elie Wiesel stepped off the cattle car at the Auschwitz subcamp Birkenau, "he smelled the stench of burning human flesh and saw the crematorium throwing its flames into the sky..."
Sonderkommandos were inmates and had contact with other inmates. Innmates were taken out to work in the manufacturing facilities in nearby towns, transferred out, escaped and were released.
So it is impossible to say that someone did not know what was supposedly happening there. Such a thing should be known by everybody... and that doesn't match at all with MOST of survivors tales.
The story says: 'two thousand per batch waited outside the gas chambers while two thousand inside were being gassed, they went in and never came out'
... impossible for other inmates to miss that....
The story says: 'screams of those being gassed could be heard'
... so then, other inmates did 'know'....
The story says: 'bodies were piled high outside the crematoriums'
... impossible for other inmates to miss that....
All photographs of heaps of corpses were taken in Western camps around the end of the war, such as Dachau, Bergen-Belsen, and Buchenwald, where historians now agree no mass murders took place. Significantly, there are no such photographs taken at the camps in which mass murder is alleged to have occurred (Auschwitz, Treblinka, Belzec, Sobibor, Chelmno, Majdanek.) These eastern camps were all in areas which came under Soviet control at war's end. It is very telling that the Soviets released no pictures of mass graves or heaps of corpses and allowed no journalists, medical professionals, or other experts to examine the camps
The story says: 'trainloads of in coming Jews were immediately sent to the gas chambers, they were gassed on arrival'
... impossible for other inmates to miss seeing the trains unloaded and the contents disappear....
The story says: 'after being gassed, luggage, shoes, and hair were left behind, it's proof of extermination'
... piles of hair & possessions left behind, the people are nowhere to be seen, but the inmates curiously wouldn't have noticed....
The Germans left thousands of Jews behind when they evacuated. This was after the Jews were given a CHOICE to leave with them or stay and await the advancing Soviets. MOST CHOSE TO RETREAT WITH THE GERMANS.
The Buna Works
The Buna Works, which Dr. Morgen mentioned, was another name for . So, two top SS officials knew about the gas chamber at Monowitz, but what about the prisoners? Did they also know about the Monowitz gas chamber. Yes!
Strangely, the Allies did not do any research on the Auschwitz camps, or they would have discovered that there was a “Gaskammer” in the Monowitz camp, where they were bombing the factories.
The most frequent criticism of President Roosevelt, who failed to stop the Holocaust, centers on the claim that U.S. planes could have bombed the tracks leading to the Auschwitz II camp, aka Birkenau. U.S. planes did, in fact, bomb the railroad tracks in Germany, which caused even more deaths of Jews, but did not stop the gassing. For example, the deaths of thousands of Jews on the “death train” to Dachau.
Incidentally, one of the American pilots who flew over Auschwitz in 1944 was young George McGovern, the future presidential nominee.
Bombing the homicidal gas chambers at Auschwitz would not have done much good because the disinfection buildings, where the clothing was deloused, could have then been used to kill the Jews.
The photo above shows one of the buildings where the clothing of the prisoners at the Auschwitz II camp was disinfected with Zyklon-B, the same gas that was used to murder the Jews in the crematoria buildings.
The Mauthausen concentration camp was established shortly after Germany annexed Austria in March 1938.
Next to the Alps, the Carpathian Range is the major mountain barrier of Europe. Extending about 900 miles (1,450 kilometers) across south-central Europe, dividing eastern Europe north and south.
The ICRC's Special Office in Arolsen keeps track of all officially documented deaths in German concentration camps of the Third Reich. A summary from December 31, 1983, documents a total of 282,077 deaths.
Since the Red Cross found more deaths at Mauthausen, the Austrian camp in the Czech corridor, than at Auschwitz, it would stand to reason most of the South East European Jews went there rather than over the Carpathian mountains into Poland. Why would the Germans ship them the way around or across the Carpathians, when the very disciplined camp of Mauthausen in Austria was much closer?
It is clear that Mauthausen housed the Hungarian, Rumanian, Czech, and Bulgarian Jews. Just due to railway routes, geographics, logistics.
The theory of the mass destruction of the Hungarian Jews is based on documents of the Nuremberg Tribunal, but such documents are by no means always genuine, or true, and only ever provide evidence for deportations - they never document an extermination. One is reminded of the example of Dachau, the concentration camp where the IMT alleged that hundreds of thousands were gassed, a claim which in the end turned out to be nothing more substantial than an atrocity propaganda lie.
The US War Refugee Board’s Final Summary Report states that more than 200,000 Jews from Budapest were exempted from deportations following negotiations with the SS. Also, in its report the International Red Cross stated that some 100,000 Jews poured into Budapest from the provinces.
The Encyclopaedia Britannica in its 1963 edition states that:
"At Mauthausen, one of the extermination camps in Austria, close to 2,000,000 people, mostly Jews, were exterminated between 1941 and 1945"
Now, the death toll has been revised:
"An estimated 197,464 prisoners passed through the Mauthausen camp system between August 1938 and May 1945. At least 95,000 died there. More than 14,000 were Jewish."
--United States Holocaust Memorial Museum, Washington, DC
An exaggeration of 1,905,000!
This camp is no longer considered by official sources who support the holocaust legend as an “extermination camp,” nor is it still claimed that any camps on German soil were either.