When Jack and Jamie Davies bought Schramsberg in 1965, the most promising part of the Diamond Mountain estate lay underground. The vineyards were fallow, and the Victorian house was in disrepair, but twelve thousand square feet of caves, dug by hand into volcanic rock a century earlier, offered exactly what their sparkling-wine project needed: a cool place for bottles to mature. Sixty-one years on, those tunnels remain the heart of the estate. The wines have changed, and the search for grapes has carried the family far beyond Napa Valley, yet the cellars continue to make that work possible.