The riverfront, monolithic brick Fort Andross Mill—which turned out countless bolts of cotton broadcloth in the 1800s and then for years stood derelict—has become one of the state’s great mixed-use spaces: antiques dealers, gallerists, and a new breed of restaurateurs all share the renovated building. Equal parts lofty café bistro and cinema, Frontier is the property’s shining star, with floor-to-20-foot-ceiling windows overlooking a rushing river, communal wood tables, and an artful homespun vibe. Sandwiches here arrive on slabs of slate, soup comes in hand-thrown ceramic bowls, and customers are expected to clear their own plates. The food is wholesome, fresh, and consistently satisfying; even the house salad with organic local greens, Parmesan, and homemade croutons and vinaigrette feels like a meal. Also worthy is the pastrami panini and cheese “market plate” (a tasty mix that includes local York Farm goat’s cheese, dried figs, and imported Belgian chocolate)—both pair nicely with a Sea Dog microbrew. And don’t miss the excellent, not-too-sweet gingersnap cookies for dessert.