At the starting line, I stamped my feet in the snow and repeated this mantra: ‘There’ll be hot wine at the end.’ The promise of plentiful wine, local color, and a unique experience had drawn me to travel on a bitingly cold, gray January weekend to Moldova, one of the least-visited countries in Europe. I was running the Mileștii Mici Wine Run, a 10k race through the world's largest wine cellar. With a total 125 miles of underground passages, there’s plenty of room to stage an ultra here; the 10K Wine Run explores a mere fraction of the tunnels. Conditions...