Hello - I've spent a lot of time researching and still can't find the best way to travel from France to Spain. We haven't booked our travel entirely yet but will most likely end our France journey in Carcassonne or Narbonne. We would like to take a train, if possible, to Barcelona. How do I book? Thanks for any suggestions.
Go to the DB train site and you will find the route you need.
Narbonne would be easier. There is a daily train from Narbonne to Barcelona at 8:24 am, arriving in Barcelona at 11:48. You can purchase tickets on Renfe.com and print at home. If you start in Carcassonne, you would leave there on the 7:35 to Narbonne to connect with the train to Barcelona. That you should book on TGV-Europe. (Might be able to book the Narbonne to Barcelona train there as well, but I did not check that.)