The Barcelona bus service offers a good solution for travelling around the city especially now that they have more bus lanes.
The main bus stop for urban buses is Plaça Catalunya. Most day buses and all night buses stop there. Barcelona’s bus station, for national and long distance bus journeys is located next to Arc de Triomf and is called Barcelona Nord bus station.
If you are planning to use the urban buses or metro more than 5 times, buy a T10 ticket (valid for 10 trips). In Nov 2011 this costs €8,45, and a single ticket costs 1,45. You can also get T50/30 tickets for €33.50 which are good for 50 trips in 30 days.
Barcelona Night buses.
There are 16 Nitbus (night bus) routes. They run about every 30 minutes. All but four of them pass through Plaça Catalunya, and some also run out of town to Badalona, Castelldefels and to the airport. Travelcards are also valid on night buses. The N17 nitbus goes from Plaça España between 22:00 and 05:30 every day of the week.