Portbou

This is not the fastest route to Barcelona. In fact it is 4 hours compared to 90 minutes.
However: Using the regional train connections gives you the opportunity to look around Portbou, a small Spanish Town at the border.
48 minutes between the train was enough to grab 2 apples from the market, visit the Walter Benjamin Memorial and go down to the water. Still having 10 minutes left. This was efficient.
However it might be worth, to let a train pass and wait 2 hours more at the beach or a café.
But this time I am travelling alone and going to Barcelona. :)Read more