Having traveled a good chunk of Europe I am here to say the 6 million baked in ovens was minor in comparison to what the rest of Europe or those in the Pacific faced overall.
About the best description I can give is from an aging Danish lady who was young during the war "It was horrible, if you were blonde and blue eyed girl you had two choices, you became their sex slave in their breeding camps or you died for resisting, it was horrible they were killing everyone in reality."
I woudl have one of the greatest moments of my life, and drink from a bottle of early times which she had shared with allied troops as they liberated Denmark.
Most older people in Europe at the time (this was 20 years ago) Would offer me a place to stay simply because I was American. They were very grateful and would of had nothing had the Allies not saved them.
Nearly every single castle in Europe was bombed, they have all been rebuilt. Most churches were as well.
In Italy you can still see bullet holes in the sides of the ageless buildings.
Overall the war was ten times more brutal than we were ever told, the same goes for hte Pacific theater against the Japanese where they would use civilians for Bayonet practices or Biological and chemical Experiments.
If you want a truly Haunting feeling, simply go and visit somewhere where civilians were massacred. For me the worst place I felt the most energy was Intramuros
In Manila Philippines,.
It was famous for taking Civilians and stacking them on top of each other Alive, in a small chamber then of course killing them, if they had not already died from suffocation.
The Philippinos HATED the Japanese for decades, remember Filipino women were sex slaves to the Japanese as well, after they were done the Japanese would kill them.
War was also far worse than Hollywood has ever put forth. My great Uncle drove ambulance and would get stuck in the bodies, he also recounted driving over people he thought were alive to get to people he knew were dead.
One of the best series of books to read and the most accurate of ww2 account is "Seven roads to hell" a screaming eagle in Bastonge. The first of the trilogy it is considered the most accurate because it was written by the soldier in England after he was waiting to come home, so all the details were fresh in his mind. The first two books are absolutely riveting and the third a bit boring but it ties things up.
The HBO Series band of brothers was based on the 101st airbone which is where he served and did a very poor job of conveying things IMO, if you saw the Series, it will give you an idea however what is in store.
The most accurate book to understand the SS is "Order of the deaths head" it is painstakingly detailed and covers the rise and fall of the SS. I will advise though this is advanced reading material, the print is small and the book incredibly large.
If you quit for even a week and try to pick it up again you will be lost, amazing book if you can stick with it however.