This entire area in full of street art and graffiti - all on legal walls.
This artwork on the metal things has been there for quite some time - at least since November 2012 - and it is not likely to be painted over anytime soon. However the walls around the metal things can change.

To get a better idea of this area and its vibes, take a stroll in the area - it is never boring and there is much more street art than is shown here on Street Art Cities. You can also look at http://grandts.dk/Aarhus/godsbanen.htm