The Venice Biennale has been running more or less continuously since 1895, and likes to think of itself as the most prestigious of all arts festivals. This year, it is playing host to no fewer than 67 national entries, 23 more than on the last occasion. Unlike the official national entries by well-established contributors, many of the newcomers are without dedicated pavilions of their own, and have located themselves in temporary venues away from the two main Biennale sites at the Giardini di Castello and the Arsenale.
The national contributions comprise approximately 230 separate works of art, ranging across all media. These complement the 110 exhibits featuring in the thematic International Exhibition, entitled this year "The Plateau of Humankind". With this show, in which "artists from all over the world offer their account of the present day", the Biennale director, Harald Szeemann, has set himself the impossible task of generating a show that tries to be all things to all people. Inevitably, it fails, but in among so many pieces there are several highlights, including strong works by Chris Cunningham, Stan Douglas, Atom Egoyan and Juliao Sarmento, Tracey Rose, Cy Twombly and Massimo Vitali. Unfortunately, many of the remaining exhibits simply name-check all the fashionable topics at the outset of the third millennium - convergence, politics, religion, gender, protest, insecurity, cruelty, the disadvantaged - and do little else besides.
On the whole, the individual contributions are much more engaging, especially Britain's presentation of a new and recent work by Mark Wallinger. Visitors approach the portico of the British pavilion along a rising, tree-lined promenade, passing buildings that house official entries from Switzerland, Venezuela and elsewhere. The British pavilion, a terracotta-coloured faux-Palladian villa, is flanked to the left and right by those of the French and the Germans so that, between them, these three once mighty empires prominently occupy the Giardini's geographical high ground. Wallinger's Facade exposes the crudity of such imperial one-upmanship, and undermines state-sponsored authority by presenting the viewer with a deceptive, one-to-one-scale, photographic image of the villa's frontage. What looks domineeringly majestic at first sight is, in fact, nothing more than an illusion, kept in place by an ugly, inflexible scaffold.
Off-site, Mike Nelson's installation The Deliverance and The Patience also puts to shame many of the works in the International Exhibition. Nelson, another Briton, constructs labyrinthine sequences of rooms within existing buildings. His visions of worlds in a box, steeped in social, historical and literary reference, are dramatic, disorientating and utterly convincing. In a disused brewery building on the Giudecca, he has fabricated a disturbing, self-reflexive theatre suggestive of human presence, but devoid of human warmth.
As cities such as Venice jostle for position on the world stage, biennales and triennales of art have become a regular fixture in cultural calendars across the globe. Paolo Baratta, the president of the Venice Biennale, has described arts festivals as "medicine" for their hosts, many of them riddled with social, political and infrastructural problems, and it is true that they do play a part in the piecemeal process of urban regeneration in centres like Delhi, Johannesburg and Shanghai. The context in which Venice and these other biennales and triennales takes place is in a state of constant geopolitical and cultural flux. As the regional and global ambience alters, so do the meanings of these events.
And so too do the ways in which selected works of art operate under their umbrellas. In his address to the round table symposium that took place in the week of the Biennale opening, Andrew Brighton, the senior curator of public programmes at Tate Modern and a trustee of Peer (the art organisation that commissioned the Mike Nelson installation), suggested that the seemingly anachronistic national pavilions in the Giardini - the concrete souvenirs of old empires - remain valid because they disrupt the curatorial conceits that threaten to overwhelm the presentation of contemporary art. This issue was developed by the artist Nick Crowe, who reminded the meeting that art is produced mostly under local conditions, but this fact is often papered over in an attempt to fit square artistic pegs into circular thematic holes. The idiosyncratic creative imperative, which is what makes art so fascinating, can be undermined by the globalising tendencies of arts festivals, and projects such as the Venice Biennale have long been the victims of their own international aspirations.
The 49th International Exhibition of Contemporary Art runs until 4 November. For further information call the Biennale infoline on (00 39) 02 54914 or visit http://www.labiennale.org