There are direct international train services to Barcelona from several European cities including Paris, Montpellier, Geneva, Zurich and Milan. Long train journeys can be made more bearable by booking a sleeping compartment on an overnight train. This option is only available on direct services. All trains entering the eastern side of Spain from France go through Port Bou/Cerbere or La Tour de Carol on the Franco-Spanish border. Traveling to Barcelona from departure points not offering a direct service may mean picking up a connection here. Most international trains arrive at Sants, Estacio de Franca or Passeig de Gracia mainline stations, all located in the centre of Barcelona.
from: http://ezinearticles.com/?Exploring-Barcelona:-Traveling-Metro&id=6403589
