Since the day Frank Lloyd Wright first got the idea to set the curved walls of the Guggenheim Museum on an angle, architects have been doing everything they can to make museum buildings as unhelpful for the display of art as they can. Gigantic walls, weird features like extended architraves, wall surfaces that are too precious to take a nail, diving boards; that sort of thing.
A typical example was the fenced gap architect Ian Athfield cut into the floor of the top gallery in Victoria University’s Adam Gallery. Charitably it might have been intended as an access for large paintings or maybe exceptionally long, thin sculptures, but realistically it is an awkward intrusion that makes the gallery uncomfortably narrow and partly blocks any long distance views. So maybe you won't be surprised to learn that the mystery object is Ian Athfield’s hole, as it were.
For the exhibition featuring Anthony McCall’s light works the gap was filled in and, even given the safety fence, the illusion that the floor extends to the wall suggests the next obvious step: pull down the fence and make the change permanent.