They depict the history and political views of both traditions and are a way of marking territory.
You can book a black taxi tour, to take you to all of them, if you are lucky with the driver he would explain you everything about their history and what had happened in each place.
About 10€ per person.
dropboy added
... and because the troubles in Belfast are alomst completely over now its great to stop and ask the locals about the art work, particularly if you come across two elderly ladies, they love nothing better than talk all day about this stuff :)
recommendation by blat
recommendation by blat
recommendation by stuart-crawford
