Gundlach Bundschu Winery is a historic winery and an outdoor concert venue located in Sonoma County. It is California's oldest continuously family-owned winery, and is the second oldest winery after Buena Vista Winery. It is still owned and operated by the founder's heirs and today led by the sixth generation, Jeff Bundschu. The winery's 320-acre (130 ha) regenerative organic certified estate vineyard, named Rhinefarm by Bavarian-born Jacob Gundlach in 1858, is located within the Sonoma Valley AVA of Sonoma County, at the crossroads of the Sonoma Valley, Los Carneros AVA and Napa Valley AVA, along the Mayacamas Mountains. They specialize in estate-driven, organically farmed Bordeaux reds and cool climate varietal wines.