If you’d like to live within easy reach of all the cultural attractions and conveniences of Barcelona but avoid the crowds and high prices, then consider Castelldefels. This charming coastal town is just 12 miles south of the heart of Barcelona—a 20-minute drive, 30-minute train ride, or 40 minutes on the bus—a trip that can cost as little as 3 euros. There are two parts to Castelldefels: the main town, which is slightly inland, and Castelldefels beach (each has its...