As I crept around a massive abandoned World War II-era train yard, I realized the Eastern European security guards had dogs with them. “Please don’t let them find me,” I thought as I wondered what would happen if the snarling hounds became aware of my presence. Silently, I picked up my Canon DSLR and snapped a photo of the giant locomotive bearing the Red Star of the Soviet Union. I also captured carriages that had been used to carry Jews to their death during the Holocaust. Overwhelmed by what was in front of me but satisfied with my pictures, I...