Here are some of my favorite things to do:
1. Enjoy the views. This picture is taken from the top of the Museum of National Art of Catalunya. It is high on a hill and the view is magnificent. The magic fountain in front of the museum is lit up at night. The monuments and columns are spectacular.
This is a picture on Las Ramblas. You will find restaurants, shops, fountains, beautiful aritechture on this major street. Stop in the market or enjoy Gaudi's work.
The old and the new architecture is stunning. Start with Gaudi's Sagrada Familia, the most visited cite in Barcelona.