The road to the Red Cross Concentration Camp is caked in frozen mud etched with tire tracks and cracking puddles. A dog jogs ahead to dig holes in the camp’s yard. The barbed-wire fence lies in a decrepit heap next to the ticket office branded with a faded swastika and, in thick capital letters, “WACHE SS”.Also, there’s also a high school next door.“Many tourists ask, ‘Oh, is this also part of the camp?’ No, it’s just a school,” explains our guide, Aleksandra Zdravkovic. She works at the tourism office of Nis, a quiet city of 190,000 in southern Serbia, and...