When I was growing up I walked past this object all the time, for years, without realising what it was. As a small kid I simply thought it was a triangular, walled-off space and never thought about it being a work of art. I just wondered why that area was walled off, why there was no way in, and what was inside (I was too short to see over it).
Later on, I figured out that it was art: I'd found the plaque nearby which said it was 'Untitled' by Donald Judd. It was 'modern art' - minimalist and blank - but it still intrigued me because it was still extremely difficult to see what, if anything, was inside its walls (I was a late bloomer). Its featureless sides frustrated small kids' attempts to climb it.
For a while I thought that was the point of the sculpture: to zone off an area you couldn't see into. Finally attaining normal height put paid to that delusion, although the thickness of the walls still inhibit an easy view into the centre.
In any case, I grew up thinking of it as just one amongst many pieces of ugly public art scattered around Adelaide. It wasn't until much later that I understood the size of Judd's reputation and how unusual it was to have regular contact with a site-specific outdoor work by him. I assumed he had stuff like this scattered all over the world. I still can't see it without thinking it's bigger than it really is.
It doesn't surprise me to hear the work described as "controversial for Adelaide" although I never heard that when living there. Adelaideans tend to be pretty reticent. Unusually, the controversy seems to have been less about the art, and more to do with the artist visiting Don Dunstan's Adelaide being an American:
In the last phases of the Vietnam war, anti-American sentiment ran high and both the exhibition and Judd’s sculpture commission caused a public outcry in Adelaide. Local academics joined with students, political groups and the media to denounce this “American imperialism” and “servility to things foreign” through protests and a debate which continued into 1975.
(Crossposted at Boring Like A Drill.)