If you are coming to Barcelona in December, Amistat Beach Hostel recommends the following activities:
Visit the Christmas Markets
Every year during Christmas time, Barcelona puts up several Markets worthwhile visiting. They sell from cheap presents, to traditional Christmas decor like the Tio de Nadal or pieces of the nativity scene. Try the traditional wines and turrons from the markets.
Go Iceskating in Plaça Catalunya
In the holidays their is an iceskating rink in Plaça Catalunya which is something different for you to do in Barcelona. This Iceskating rink is active from November 20th to January 6th.
Visit the Magic Fountain near MontJuic
A nice evening plan is to enjoy the fountains that dance with the sound of the music. During December, they offer a special show on Fridays and Saturdays from 7-9 pm, as well as Christmas and New Years day.