Visiting Auschwitz

Kraków is the nearest big city, with lots to do/see. Auschwitz/Birkenau is a local bus ride away. In Krakow you should visit the Jewish Museum, the deportation grounds, and the Schindler Museum.

As stated by Zoe, Krakow is the nearest city and there is a lot to do there regarding the Holocaust. Whether you spend much time in Krakow and take advantage of it or not, it is still probably the best base for Auschwitz.

You can find some very moving Concentration Camp Memorials nearer to cities that are still on your primary route, without detouring to Poland. Dachau (near Munich) is not as complete as others, but Mauthausen (2 hours from Vienna or Salzburg by train) is very worthwhile, as is Sachsenhausen (about 1 hour from Berlin). See also http://www.ricksteves.com/watch-read-listen/read/articles/sobering-sites-of-nazi-europe.

Jonah, if your desire is limited to touring Auschwitz (as opposed to touring any concentration camp) then Krakow is the most convenient access point. Like Ray I took a guided tour from Krakow which met my needs better than just hopping a train or bus to the camp. If you feel that you might be able to get a comparable experience by touring another camp, you can read some opinions from others on this forum. I posted this thread before my trip last year and it contains some good thoughts.

https://community.ricksteves.com/travel-forum/general-europe/which-concentration-camp

Highly recommend the Schindler Museum - it is wonderful....a real surprise!!!!

"Fascinates" is an interesting way to describe an interest in seeing a concentration camp. I also have been to both Dachau and Munthausen and was very moved by the experience. You might consider one of those or another one on your route. Just be sure you are picking one that has something to see, not just a monument.

Be ready to cry, it's a powerful experience.