At first i thought it might have been an art installation, however i could not see any signs of the slabs being recently moved. I could also see how far the water had been flowing so it couldn't have been going on for too long, i rather think it's a leaking water pipe.
Hmmm, turns out it's actually an art installation... http://konstframjandet.se/aktuellt/invigning-magnus-thierfelder/
Thanks Ludde :)
