When it comes to contemporary art, though, it's easy to have mixed feelings about this wish to keep artworks going forever. One way of looking at art since 1960 or so is as an endless flight from permanence, with artists seeking ever more candid and aggressive ways to assert the mortality of the things they make. In the hands of the shaggy, rule-averse, process-loving artists of the sixties and seventies, art slumped, crumbled, scattered, disappeared underwater and sometimes evaporated into thin air.

Yet no sooner were those gestures made than the museum (carrying its black bag full of potions and lotions) stepped into the breach, seeking to preserve for ever and a day things that were designed to pass. And there the artworks now lie in their climate-controlled coffins – pop collages made from acid-rich cardboard, post-minimalist sculptures fashioned from yellowing latex, all so vulnerable to light and movement that they barely stand a chance of being seen. The nobler path, I often find myself thinking, would be simply to let these artworks die – to view them in the same spirit we view performances or flowers, and enjoy them while they last.

And that's why I'm thrilled by the sight of the trailers and previews for the new documentary about German artist Anselm Kiefer and his 'hill studio' complex at Barjac in the south of France. Before seeing these clips I'd heard a few tempting facts about the size of Kiefer's studio, among them the story about him using a pushbike to get from one point to another within it. But that was no preparation for the staggering images that unfold in these two clips, of a combined warren and labyrinth where art lives out in the elements and will eventually subside into them. A total artwork that declares its own mortality and welcomes its own eventual ruin.

And in a city like Christchurch, where in the Avonside red zone you can see nature already taking hold of whole streets, there is no missing the poignancy of the line from Kiefer that gives the film its title: over your cities grass will grow.