The State Museum of Auschwitz-Birkenau and Remember.org offer photographs and virtual tours of Auschwitz I and Birkenau. This website can be confusing to navigate and contains a blend of modern and historical photos. However, it does offer excellent views of both comps.
“Preparatory Work in Auschwitz.” Excerpt from Anatomy of the Auschwitz Death Camp. (Note: This is a secondary source.) Braham was a Romanian Jew and Holocaust survivor. He was not imprisoned at Auschwitz. After his immigration to the U.S. he earned his credentials as a historian and political scientist, specializing in the Holocaust. See also.
The Vrba-Wetzler Report. Background info about and original document from two Slovakian Jews who escaped from Auschwitz in April 1944. See also for readability.
The Auschwitz Album. May-June 1944. These are the only known photos that show the process of Jews arriving at Auschwitz-Birkenau.
“Three Survivors of Buchenwald Concentration Camp.” 16 April 1945. Photo. Docs Teach. National Archives. Note: This photo has a graphic content warning. It shows three nude men. Two are seated with garments covering their laps. The other is shown from a side-rear view. The point of the photo is to show how emaciated the men have become. The caption says their average weight is 70 pounds.
Elie Wiesel: On the Atrocities in Sudan. Remarks delivered at the Darfur Emergency Summit, convened at the Graduate Center of the City University of New York on 14 July 2004 by the American Jewish World Service and the United States Holocaust Memorial Museum.