I learned a lot about libations last weekend while visiting not one but two Elysian Fields of alcohol within a short stroll of each other on the scenic Alameda waterfront. First was the Rock Wall Wine Company, whose Open House on Saturday afternoon featured food booths, wine tasting and tours of the vast facility, which is located inside a 40,000-square-foot historic former military airplane hangar. It was inspiring to learn how grapes from the Napa Valley, Sonoma County and even nearby Contra Costa County are transformed into Cabernet Sauvignon, Zinfandel and Petite Sirah a virtual stone’s throw from downtown Oakland. Let’s raise a glass to urban winemaking. My favorite wines…