This small bookshop specializing in artists publications is located since this summer in the Raval neighbourhood. They have a very meticulous selection of publications made or conceived by artists (not publications about art). I've discovered there small presses, publications and artists that I really love.
I only recommend walking around the Barceloneta beach at sunset, there are fewer people and in the fall and spring seasons is very nice to sit on a terrace watching the sea and entertaining yourself with the activities of the area.