Napa Valley AVA is an American Viticultural Area located in Napa County, California, USA. Napa Valley is considered one of the top wine regions in the United States and one of only nine Great Wine Capitals on earth, with a history dating back to the nineteenth century. The combination of Mediterranean climate, geography and geology of The Valley are conducive to growing quality wine grapes. John Patchett established the Napa Valley's first commercial vineyard in 1858.