Hadid slyly imposes her trademark style, all right: the building looks as if it is made of a number of layers, all caught at a moment when they are just starting to slide apart. She brings the sidewalk into the building and curves it upwards to form the foyer wall - that's Zaha indulging her obsession with warping the ground plane. But all of this is underplayed. It's only really hinted at. What Hadid is holding back is the interior. From outside, you think you've got the building in one. Inside, she mixes it up. You can get lost in there. What level am I on? Is that up or down? What's through that door? Where's that noise coming from? The opening exhibition had far too much second-division conceptual stuff in it, but the experience of wandering from space to space was delightful.

The CAC, as it is known, does not have a permanent collection. In this it is like London's Hayward Gallery or Gateshead's Baltic. So - apart from circumstantial evidence in the form of the history of exhibitions staged by the CAC from 1939 onwards in its previous homes - there was nothing in the way of objects to plan the museum round. "We chose her because she really understood contemporary art," says the CAC director, Charles Desmarais. "And we needed someone who could do a building that would symbolize the key values of the Contemporary Arts Center, would tie our programmes to the city in a much more direct way than before."