This episode wanders into supernatural territory in the search for unmarked graves. It began innocently enough: A listener asked us about Nashville’s oldest structures. But as we visited some of the city’s oldest homes, we found family graveyards that date back 200 years or more — and some owners, it turns out, relied on a generations-old practice with mysterious power to find unmarked graves. Which led us to the question: What’s up with “water-witching” in Nashville?