Independent spirits have been celebrated in Philadelphia since the Founding Fathers raised their mugs over a scribbled draft of the Declaration of Independence. Here, in a city still proud of its indie ways, small-batch bourbons and house-made bitters ignite a cocktail culture extraordinaire. At Vernick Food & Drink (2031 Walnut St., 267.639.6644), a made-to-order Manhattan starts with a bourbon, then it’s up to you—suggest flavor notes like maple, cherry or cardamom, and your cocktail is custom made. Why have a regular old fashioned at Red Owl Tavern (433 Chestnut St., 215.923.2267, when you can have The Spaniard, a brooding mix of Buffalo Trace bourbon, Amontillado sherry and Bitter Truth chocolate bitters. Barrel aging has long been the secret to deeper flavors in everything from whiskey to port. The crew at Pub & Kitchen (1946 Lombard St., 215.545.0350) finds that, like fine wine, cocktails including Manhattans and Negronis get much better after a month in an oak barrel.