You can find many different types of Tiles in Barcelona. Especially 'Eixample' neighborhood is best place to see tiles.
2. Tree's name tag
In the park or avenue or just around corner you can find name tag for each trees.
Recently, city council removing Crosswalk and draw again to make better connection to street. Crosswalk can be diagonal or other direction not only straight.
4. Trash can
For smokers ;-)
5. Bicycle path
Barcelona have well connection with bicycle path. A lot of people use bicycle for daily travel to work or school.
That reduce car traffic as well as air pollution.