Poland
Several years ago, I had the profound experience of visiting Auschwitz. We had just left Birkenau (part of the camp) when I realized that I wasn't ready to go, that I needed more time to absorb the experience. Upon returning, we ran into this group of orthodox Jewish men. We greeted each other quietly and ended up walking together, alternating between periods of silence, prayer, and song. The experience was deeply moving and helped me feel more anchored in this most disturbing of places. In the photo, we are at the site of the "ramps" where the Nazis decided which of the new arrivals would be killed immediately (80%) or become slave labor. 
Medfield State Psychiatric Hospital, Massachusetts
In August, I visited this shuttered psychiatric hospital to take photographs, not knowing what to expect. It was an eerie place that brought back disturbing memories from one of my early social work jobs in a similar facility. The buildings were closed so we couldn't go inside. (You can find interior shots on the internet if you're interested.) Plans are underway to convert the site into a housing development, something that's been done with most of the state's other psychiatric facilities. 
I was surprised by how much there was to photograph. I was most taken by the muted, subtle and interesting colors - all unexpected in what was undoubtedly a very dark place.