Tarragona

Tarragona can be covered in a full day: the seafront Roman amphitheater, the city wall and the medieval old town cover the essentials. May-September combines good weather with nearby beaches like Platja Llarga. It's one of Catalonia's most affordable cities, noticeably cheaper than Barcelona or Sitges. Its differentiator is the sheer amount of preserved Roman heritage: it was the capital of Roman Hispania (Tarraco) and today holds one of Spain's most complete Roman archaeological complexes, a UNESCO World Heritage Site.