Who ever thought wine caves would be trending the day after the Democratic debate? South Bend, Indiana, mayor and presidential hopeful Pete Buttigieg drew criticism after holding a pricey fundraiser at a Napa Valley wine cave. But what is a wine cave? They've become a popular feature at high-end restaurants across the country. Inside Edition visited the wine cave at Rails Steak House in Towaco, New Jersey, to learn more about how they keep wine at the right temperature and create ambiance.