Don't get too stuck on trying to find the perfect word. The point that you need to remember is you want to convey a specific feeling to a reader, and the feeling doesn't necessarily have to be a positive one.

As the articles I link to point out, visiting one of these sites brings a flood of emotions, and each person will experience it differently. There will never be an ideal word to describe something like the holocaust with.

My suggestion would be to look for other papers or blog posts where people reflect on visiting a holocaust memorial and see if it helps give you any ideas. The one word that popped into my mind when I scrolled into view of a picture of coffin-sized ovens was simply: surreal.

Here are a couple pages I found after doing a quick Google News search for "visit holocaust memorial" that deal with visiting Auschwitz specifically:

• http://www.studentnewspaper.org/how-should-we-remember-the-holocaust/
• http://www.ajc.com/news/news/local/making-the-grade-high-schoolers-get-up-close-look-/npdhR/

Some other words pulled from the articles:

• life-changing
• moving
• heavy

The one word that popped into my mind was: surreal.

Here is a relevant excerpt from the article High schoolers get up-close look at Holocaust - AJC.com:

“When he was a freshman, I told him to take the class because it is literally life-changing,” he said. “The trip was moving; it evoked a broad spectrum of emotions. Visiting Krakow and Auschwitz was very heavy; it’s so hard to wrap your head around how many people were slaughtered when you’re walking through the same gas chambers."